Electric Power Conversion Apparatus

ABSTRACT

An electric power conversion apparatus includes a channel case in which a cooling water channel is formed; a double side cooling semiconductor module that has an upper and lower arms series circuit of an inverter circuit; a capacitor module; a direct current connector; and an alternate current connector. The semiconductor module includes first and second heat dissipation metals whose outer surfaces are heat dissipation surfaces, the upper and lower arms series circuit is disposed tightly between the first heat dissipation metal and the second heat dissipation metal, and the semiconductor module further includes a direct current positive terminal, a direct current negative terminal, and an alternate current terminal which protrude to outside. The channel case is provided with the cooling water channel which extends from a cooling water inlet to a cooling water outlet, and a first opening which opens into the cooling water channel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/686,375, filed Apr. 14, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/546,458, filed Nov. 18, 2014, now U.S. Pat. No.9,042,101, issued May 26, 2015, the priority of which is claimed here,which is a continuation of U.S. patent application Ser. No. 13/788,805,filed Mar. 7, 2013, now U.S. Pat. No. 8,917,509, issued Dec. 23, 2014,the priority of which is claimed here, which is a continuation of U.S.patent application Ser. No. 13/152,505, filed Jun. 3, 2011, now U.S.Pat. No. 8,416,574, issued Apr. 9, 2013, the priority of which isclaimed here, which is a continuation of U.S. patent application Ser.No. 12/388,910, filed Feb. 19, 2009, now U.S. Pat. No. 7,978,471, issuedJul. 12, 2011, the priority of which is claimed here, and which in turnclaims priority under 35 U.S.C. §119 to Japanese Patent Application No.2008-061185, filed Mar. 11, 2008, the priority of which is also claimedhere, the entire disclosures of which afore-mentioned documents areherein expressly incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electric power conversion apparatusthat includes an inverter circuit.

2. Description of Related Art

As a conventional technology intended to increase heat dissipationefficiency of a semiconductor module by efficiently transferring heatfrom the semiconductor module to a cooler, patent reference literature 1(Japanese Laid Open Patent Publication No. 2005-175163) discloses, forexample, a cooling structure. According to the description of patentreference literature 1, a semiconductor module is inserted in a holeformed in a cooler for inserting a semiconductor module to allow heat tobe released from a surface of the semiconductor module that abuts thehole for inserting the module. More particularly, a layer of soft metalis applied on the surface of the semiconductor module that abuts thehole for inserting the module so that heat is released to the coolerthrough the layer of the soft metal.

A conventional technology intended to balance the cooling efficiency andthe assemblability of a semiconductor element for use in an inverterincludes, for example, an inverter disclosed in patent referenceliterature 2. According to the description of patent referenceliterature 2 (Japanese Laid Open Patent Publication No. 2005-237141), anaccommodating portion that accommodates a power card of which both sidesof a semiconductor device are sandwiched by heat dissipation plates anda cycling path that circulates a coolant around the power card isformed, and an insulating resin is filled between the power card and theaccommodating portion, and the insulating resin is cured to fix thepower card.

A conventional technology for a cooling structure intended to improvecooling capacity with a decreased burden of assembling a semiconductormodule is disclosed in, for example, patent reference literature 3.According to the description of patent reference literature 3 (JapaneseLaid Open Patent Publication No. 2006-202899), a block is provided inwhich a semiconductor module is housed inside thereof and heatdissipation planes are provided on its front and rear sides to dissipateJoule heat generated in the semiconductor module. The block is insertedinto a cooling water channel formed in a case so as to cause the frontand rear sides of the block to face the cooling water channel.

A conventional technology of a cooling structure that is capable ofcooling a smoothing capacitor as well as cooling both sides of asemiconductor module is disclosed in, for example, patent referenceliterature 4 (Japanese Laid Open Patent Publication No. 2001-352023).According to the description of patent reference literature 4,semiconductor modules are provided on each side of a smoothingcapacitor, and a switchback-shaped flat coolant tube is used to form acoolant channel along the both sides of the semiconductor modules andalong the smoothing capacitor, achieving a high level of heatdissipation efficiency without leakage.

In recent years, in automobiles, for example, various in-vehicle systemsfor vehicles including a drive system for a vehicle are operatedelectrically. In order to electrically operate the in-vehicle systems,it becomes necessary to add freshly or in place of a component of theconventional system an electrical machine that drives a driven body andan electric power conversion apparatus that controls the power suppliedto a rotating electrical machine from an in-vehicle power source inorder to control driving of the rotating electrical machine.

The electric power conversion apparatus, e.g. for an automobile, hasfunctions to convert direct current power supplied from the in-vehiclepower source to alternating current power for driving a rotatingelectrical machine and to convert alternating current power generated bythe rotating electrical machine to direct current power for supplying tothe in-vehicle power source. While electrical energy converted by anelectric power conversion apparatus tends to increase, automobiles tendto be small in size and weight in general. Thus, increase in size andweight of an electric power conversion apparatus is limited. Anin-vehicle electric power conversion apparatus, in comparison with anindustrial one, is required to be used in an environment with greattemperature change. Therefore, an electric power conversion apparatusrelatively small in size that converts high power and assures a highlevel of reliability even in a high-temperature environment is required.

The electric power conversion apparatus includes an inverter circuit andperforms power conversion between direct current power and alternatingcurrent power by the operation of the inverter circuit. In order toperform this power conversion, it is necessary to repeat action ofswitching between a blocked state and a conduction state of a powersemiconductor that constitutes the inverter circuit (switching action).When the switching action is performed, a large amount of heat isgenerated in the power semiconductor. Because of the heat generated by asemiconductor chip, which is the power semiconductor of the invertercircuit, upon the switching action, the temperature of the semiconductorchip is increased. For this reason, it is important to prevent thistemperature increase.

According as power to be converted increases, the amount of heatgenerated in the semiconductor chip increases. To cope with this, it isnecessary to increase the size of the semiconductor chip or the numberof the semiconductor chips to be used, resulting in an increase in sizeof the electric power conversion apparatus. As a measure of preventingsuch an increase in size of the electric power conversion apparatus, itis conceivable to improve cooling efficiency of the semiconductor chips.

For example, patent reference literatures 1 to 3 present proposals toincrease the cooling efficiency of the semiconductor chips. Althoughimprovement in cooling efficiency of a semiconductor chip obviouslyleads to miniaturization in the semiconductor chip, it does notnecessarily contribute to size reduction of the overall electric powerconversion apparatus. For instance, an improvement in cooling efficiencyof a semiconductor chip may result in a complex structure of the overallelectric power conversion apparatus. Thus, although the semiconductorchip may be miniaturized, the overall electric power conversionapparatus may not be miniaturized significantly.

Accordingly, in order to prevent an increase in size of the overallelectric power conversion apparatus, it is necessary to improve thecooling efficiency of the semiconductor chip with the overall electricpower conversion apparatus considered, and necessary to preventelectrical or mechanical complexity in the overall electrical powerconversion apparatus. The electrical complexity results from, forexample, complex electrical wiring between the semiconductor modulehaving a semiconductor chip incorporated therein and a capacitor module,a driver board, or an alternate current connector. The mechanicalcomplexity results from complex mounting of a semiconductor module tothe channel case or complex mounting of a capacitor module.

In the technologies disclosed in the patent reference literatures 1 to3, miniaturization of the overall electric power conversion apparatus isnot sufficiently considered, and specific disclosure of the dispositionof capacitor modules or the cooling structure is insufficient. Thepatent reference literature 4 discloses a disposition structure in whichthe cooling of a smoothing capacitor, in addition to the cooling of asemiconductor module, is intended. However, the disposition structuredoes not adopt a water-cooling method but employs a cooling method withwhich the semiconductor module and the smoothing capacitor are cooledthrough a coolant tube connected to a coolant pipe of an externalrefrigeration cycle device. Furthermore, an arrangement of othercomponents such as a circuit board that is connected to thesemiconductor module is not elaborated, thereby leaving an issue inminiaturization of the overall electric power conversion apparatus.

The present invention is to provide a technology for miniaturization ofan overall electric power conversion apparatus. The electric powerconversion apparatus according to an embodiment of the present inventiondescribed hereinafter intends to provide not only the technology forminiaturization but also improvement in reliability, productivity, andcooling efficiency, which are necessary to commercialize the device.

SUMMARY OF THE INVENTION

An electric power conversion apparatus according to a first aspect ofthe present invention comprises: a channel case in which a cooling waterchannel is formed; a double side cooling semiconductor module thatcomprises an upper and lower arms series circuit of an inverter circuit;a capacitor module; a direct current connector; and an alternate currentconnector, wherein: the semiconductor module comprises a first and asecond heat dissipation metals whose outer surfaces are heat dissipationsurfaces, the upper and lower arms series circuit is disposed tightlybetween the first heat dissipation metal and the second heat dissipationmetal, and the semiconductor module further comprises a direct currentpositive terminal, a direct current negative terminal, and an alternatecurrent terminal which protrude to outside; the channel case is providedwith the cooling water channel which extends from a cooling water inletto a cooling water outlet, and a first opening which opens into thecooling water channel through which the semiconductor module is insertedinto the cooling water channel in a removable manner; the channel caseis further provided with a second opening through which the capacitormodule is placed; the first opening for the semiconductor module isdisposed on both sides of the second opening for the capacitor module;and a plurality of the semiconductor module are arranged through thefirst opening provided on the both sides so that a long side of thefirst heat dissipation metal and the second heat dissipation metal ofeach of the semiconductor modules is set along a direction along whichcooling water flows.

An electric power conversion apparatus according to a second aspect ofthe present invention comprises: a channel case in which a cooling waterchannel is formed; a double side cooling semiconductor module thatcomprises an upper and lower arms series circuit of an inverter circuit;a capacitor module; a direct current connector; and an alternate currentconnector, wherein: the semiconductor module comprises a first and asecond heat dissipation metals whose outer surfaces are heat dissipationsurfaces, the upper and lower arms series circuit is disposed tightlybetween the first heat dissipation metal and the second heat dissipationmetal, and the semiconductor modules further comprises a direct currentpositive terminal, a direct current negative terminal, and an alternatecurrent terminal which protrude to outside; the channel case is providedwith the cooling water channel which extends from a cooling water inletto a cooling water outlet, and a first opening which opens into thecooling water channel through which the semiconductor module is insertedinto the cooling water channel in a removable manner; the channel caseis further provided with a second opening through which the capacitormodule is placed; the first opening for the semiconductor module isdisposed on both sides of the second opening for the capacitor module;and a driver board, on which a drive element for driving the invertercircuit constituted with the upper and lower arms series circuit ismounted, is provided on an upper surface of the capacitor module placedthrough the second opening, and a control board, on which a controlelement for controlling the inverter circuit is mounted, is provided onthe driver board.

An electric power conversion apparatus according to a third aspect ofthe present invention comprises: a channel case in which a cooling waterchannel is formed; a double side cooling semiconductor module thatcomprises an upper and lower arms series circuit of an inverter circuit;a capacitor module; a direct current connector; and an alternate currentconnector, wherein: the semiconductor module comprises a first and asecond heat dissipation metals whose outer surfaces are heat dissipationsurfaces, the upper and lower arms series circuit is disposed tightlybetween the first heat dissipation metal and the second heat dissipationmetal, and the semiconductor module further comprises a direct currentpositive terminal, a direct current negative terminal, and an alternatecurrent terminal which protrude to outside; the channel case is providedwith the cooling water channel which extends from a cooling water inletto a cooling water outlet, and a first opening which opens into thecooling water channel through which the semiconductor module is insertedinto the cooling water channel in a removable manner; the channel caseis further provided with a second opening through which the capacitormodule is placed; the first opening for the semiconductor module isdisposed on both sides of the second opening for the capacitor module;and each of the first heat dissipation metal and the second heatdissipation metal of the semiconductor module comprises, in its outersurface, a fin-shaped part with recesses through which the cooling waterflows, and the semiconductor module is inserted firmly through the firstopening on the both sides.

An electric power conversion apparatus according to a fourth aspect ofthe present invention comprises: a channel case in which a cooling waterchannel is formed; a double side cooling semiconductor module thatcomprises an upper and lower arms series circuit of an inverter circuit;a capacitor module; a direct current connector; and an alternate currentconnector, wherein: the semiconductor module comprises a first and asecond heat dissipation metals whose outer surfaces are heat dissipationsurfaces, the upper and lower arms series circuit is disposed tightlybetween the first heat dissipation metal and the second heat dissipationmetal, and the semiconductor module further comprises a direct currentpositive terminal, a direct current negative terminal, and an alternatecurrent terminal which protrude to outside; the channel case is providedwith the cooling water channel which extends from a cooling water inletto a cooling water outlet, and a first opening which opens into thecooling water channel through which the semiconductor module is insertedinto the cooling water channel in a removable manner; the channel caseis further provided with a second opening through which the capacitormodule is placed; the first opening for the semiconductor module isdisposed on both sides of the second opening for the capacitor module;and a positive terminal and a negative terminal of the capacitor moduleare connected to the direct current positive terminal and the directcurrent negative terminal of the semiconductor module respectivelythrough a connecting member identical to one another in shape and inlength.

According to a fifth aspect of the present invention, in the powerconversion device according to the fourth aspect, the capacitor modulehouses a plurality of capacitor blocks; and a positive terminal and anegative terminal of each of the capacitor blocks are connected to thedirect current positive terminal and the direct current negativeterminal of each of the semiconductor modules respectively through aconnecting member identical to one another in shape and in length.

According to a sixth aspect of the present invention, in the electricpower conversion apparatus according to the first aspect, in addition tothe first opening provided on the both sides of the second opening forthe capacitor module, a return opening is provided to link the firstopening on one side and the first opening on another side with eachother, and the cooling water channel is configured so that the coolingwater makes U-turns at three locations throughout the cooling waterchannel.

According to a seventh aspect of the present invention, in the electricpower conversion apparatus according to the sixth aspect, the coolingwater inlet and the cooling water outlet are provided on a front sidesurface of the channel case, with one of the cooling water inlet and thecooling water outlet disposed on either right or left side of the frontside surface, and the return opening is provided on a front side of thechannel case; the semiconductor modules comprise a first semiconductormodule disposed on the one side of the second opening for the capacitormodule, and a second semiconductor module disposed on the other side ofthe second opening for the capacitor module, with the second heatdissipation metal of each of the first and second semiconductor modulesfacing toward the capacitor module; and the cooling water channel isconfigured so that the cooling water flows in order from the coolingwater inlet, a first heat dissipation metal of the first semiconductormodule, a second heat dissipation metal of the first semiconductormodule, a path formed by the return opening on the front side, a secondheat dissipation metal of the second semiconductor module, a first heatdissipation metal of the second semiconductor module, to a cooling wateroutlet section.

According to a eighth aspect of the present invention, in the electricpower conversion apparatus according to the sixth aspect, the coolingwater inlet and the cooling water outlet are provided on a front sidesurface of the channel case on one of a right side and a left side ofthe front side surface, and the return opening is provided on a sideopposite from the front side surface of the channel case; thesemiconductor modules comprise a first semiconductor module disposed onthe one side of the second opening for the capacitor module, and asecond semiconductor module disposed on the other side of the secondopening for the capacitor module, with the second heat dissipation metalof each of the first and second semiconductor modules facing toward thecapacitor module; and the cooling water channel is configured so thatthe cooling water flows in order from the cooling water inlet, a firstheat dissipation metal of the first semiconductor module, a path formedby the return opening on the opposite side, a first heat dissipationmetal of the second semiconductor module, a second heat dissipationmetal of the second semiconductor module, the path formed by the returnopening on the opposite side, a second heat dissipation metal of thefirst semiconductor module, to the cooling water outlet.

According to a ninth aspect of the present invention, in the electricpower conversion apparatus according to the eighth aspect, thesemiconductor modules further comprises a third semiconductor moduledisposed in the path formed by the return opening on the opposite side,in addition to the first semiconductor module disposed in a path on theone side and the second semiconductor module disposed in a path on theother side; and the first semiconductor module, the second semiconductormodule and the third semiconductor module each correspond to one ofthree phases.

According to a tenth aspect of the present invention, in the electricpower conversion apparatus according to the first aspect, a firstsemiconductor module group comprising a first inverter circuitconstituted with first upper and lower arms series circuits for U-phase,V-phase, and W-phase is arranged through the first opening provided onone side of the second opening for the capacitor module; and a secondsemiconductor module group comprising a second inverter circuitconstituted with second upper and lower arms series circuits forU-phase, V-phase, and W-phase is arranged through the first openingprovided on another side of the second opening for the capacitor module.

According to a eleventh aspect of the present invention, the electricpower conversion apparatus according to the first aspect 10 furthercomprises: a driver board, disposed on an upper surface of the capacitormodule, that drives an inverter circuit of each semiconductor module,and that bridges between the first semiconductor module group and thesecond semiconductor module group to be used for both the firstsemiconductor module group and the second semiconductor module group.

According to a twelfth aspect of the present invention, in the electricpower conversion apparatus according to the second aspect, the channelcase is formed at least with a lower case and an upper case; a directcurrent connection member that connects terminals of the capacitormodule and the semiconductor module with each other, an alternatecurrent connection member that connects an alternate current terminal ofthe semiconductor module and the alternate current connector, the driverboard, and the control board are provided in this order on the uppersurface of the capacitor module which is placed through the secondopening provided in the lower case; and the upper case is fitted on thelower case so as to house the direct current connection member, thealternate current connection member, the driver board, and the controlboard.

According to a thirteenth aspect of the present invention, in theelectric power conversion apparatus according to the first aspect, thesemiconductor module comprises an upper arm IGBT chip, an upper armdiode chip, a lower arm IGBT chip, and a lower diode chip; and the upperarm IGBT chip and the lower arm IGBT chip are arranged on a same levelsurface along a direction of the cooling water flowing through the firstand second heat dissipation metals.

According to a fourteenth aspect of the present invention, in theelectric power conversion apparatus according to the first aspect, thechannel case comprises an accommodating portion to house the capacitormodule inserted through the second opening; and a thermal conductionresin is filled between an inner wall of the accommodating portion andan outer wall of the capacitor module.

According to a fifteenth aspect of the present invention, in theelectric power conversion apparatus according to the first aspect, thechannel case comprises an accommodating portion to house the capacitormodule inserted through the second opening; and a thermal conductiongrease is applied to an inner wall of the accommodating portion and anouter wall of the capacitor module.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of one ormore preferred embodiments when considered in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram presenting a control block of a hybridautomobile.

FIG. 2 is a diagram illustrating circuitry of an electric system fordriving a vehicle that is provided with an inverter device including anupper and lower arms series circuit and a control unit, an electricpower conversion apparatus constituted by capacitors connected to thedirect current side of the inverter device, a battery, and a motorgenerator.

FIG. 3 is a diagram showing circuitry of an electric power conversionapparatus in which two upper and lower arms series circuits are used tooutput alternating current for each phase to the motor generator.

FIG. 4 is a perspective view showing an appearance configuration of theelectric power conversion apparatus according to an embodiment of thepresent invention.

FIG. 5 is an exploded perspective view of the electric power conversionapparatus according to an embodiment of the present invention.

FIG. 6 is a plan view of the electric power conversion apparatusaccording to an embodiment of the present invention from which an uppercase has been removed.

FIG. 7 is an exploded perspective view of the electric power conversionapparatus according to an embodiment of the present invention, showingthe electric power conversion apparatus as shown in FIG. 5 from whichthe upper case, the control board, the driver board, and the alternatecurrent connectors are omitted so as to illustrate the configuration ofa semiconductor module.

FIG. 8 is a perspective view of the power system of the semiconductormodule shown in FIG. 7 with alternate current connectors and a directcurrent connector added thereto.

FIG. 9 is an exploded perspective view of the power system of thesemiconductor module shown in FIG. 8.

FIG. 10 is an exploded cross-sectional view showing the configuration ofthe semiconductor module shown in FIG. 7 as seen from the direction offlow of the cooling water.

FIG. 11 is a cross-sectional view of the electric power conversionapparatus according to the present embodiment from which the upper casehas been removed as seen from the direction of flow of the coolingwater.

FIG. 12 is a cross-sectional view of the semiconductor module, thecapacitor module, and the cooling water channel according to the presentembodiment as seen from above.

FIG. 13 is a perspective view showing an appearance configuration of thesemiconductor module of the electric power conversion apparatusaccording to an embodiment of the present invention.

FIG. 14 is a cross-sectional view of the semiconductor module accordingto the present embodiment as taken through A-A line shown in FIG. 13.

FIG. 15 is an exploded perspective view of the semiconductor moduleaccording to the present embodiment.

FIG. 16 is a cross-sectional view of the semiconductor module accordingto the present embodiment as taken through B-B line shown in FIG. 15.

FIG. 17 is a perspective view showing an inside structure of an upperand lower arms series circuit of the semiconductor module according tothe present embodiment.

FIG. 18 is a perspective view showing the configuration of the upper andlower arms series circuit disposed in a fin (side A) of thesemiconductor module according to the present embodiment.

FIG. 19 is a perspective view of components disposed in the fin (side A)of the semiconductor module.

FIG. 20 is a perspective view of components disposed in the fin (side B)of the semiconductor module.

FIG. 21 is a perspective view showing a structure of a terminalconnection between the semiconductor module and the capacitor moduleaccording to the present embodiment.

FIG. 22 is a schematic structural layout illustrating reduction ofwiring inductance in the semiconductor module and the capacitor moduleaccording to the present embodiment.

FIG. 23 is a schematic equivalent circuit diagram illustrating reductionof wiring inductance in the semiconductor module and the capacitormodule according to the present embodiment.

FIG. 24 is a perspective view showing another example of an arrangementof a positive terminal and a negative terminal of the semiconductormodule according to the present embodiment.

FIGS. 25A to 25C show explanatory diagrams illustrating configurationexamples of a water channel and a plurality of semiconductor modulesaccording to the present embodiment.

FIGS. 26A and 26B show explanatory diagrams illustrating otherconfiguration examples of a water channel and a plurality ofsemiconductor modules according to the present embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

The characteristic features of an embodiment of the present invention issummarized as below. The embodiment of the present invention isconfigured to include a semiconductor module in which heat dissipationmetals sandwich a semiconductor chip for an upper arm and asemiconductor chip for a lower arm that constitute a series circuithaving an upper arm and a lower arm of an inverter circuit, a channelcase which also functions as a lower case for cooling the semiconductormodule, a center opening and side openings provided on the center andboth sides of the center opening of the channel case, a capacitor moduleslotted in the center opening and the semiconductor modules slotted inthe side openings, so as to cool the capacitor module, in addition tothe semiconductor modules, in the channel case. Moreover, a driverboard, a control board, and an alternate current bus bar are provided onthe upper surface of the capacitor module for the purpose ofminiaturization. A resin or grease with thermal conductioncharacteristics is filled in a gap between an inner wall of the centeropening and an outer wall of the capacitor module after the capacitormodule is slotted in the center opening of the channel case, therebycooling the capacitor module effectively.

The following is a detailed description of a semiconductor moduleaccording to an embodiment of the present invention with reference tothe attached drawings. First, technical problems on improvements andinnovations on the electric power conversion apparatus according to thepresent embodiment and the outline of the technology to solve thetechnical problems are described.

The electric power conversion apparatus according to the embodiment ofthe present invention is made taking into consideration the followingtechnical viewpoints so that they meet needs. One of the viewpoints is atechnology of miniaturization, that is, a technology of preventing anelectric power conversion apparatus from increasing in size as much aspossible, which tends to increase with an increase in power to beconverted. Another one of the viewpoints is a technology related toimprovement of reliability of the electric power conversion apparatus.Yet another one of the viewpoints is a technology related to improvementof productivity of the electric power conversion apparatus. The electricpower conversion apparatus according to the embodiment of the presentinvention is designed according to each of the above-mentioned threeviewpoints, and moreover, a viewpoint combined the above mentionedviewpoints. The features of the electric power conversion apparatus inthe respective viewpoints are outlined hereinbelow.

(1) Explanation on Miniaturization Technology

The electric power conversion apparatus according to the presentembodiment has the following structure. That is, a series circuit of theupper and lower arms of an inverter is housed in a semiconductor modulewith a cooling metal on each side. The semiconductor module is immersedin cooling water (slot-in structure) to cool the cooling metal on eachside of the semiconductor module with the cooling water. With thisstructure, cooling efficiency is improved, achieving miniaturization ofthe semiconductor module. As a specific structure, an electricinsulation member such as an electric insulation sheet or an electricinsulation plate made of a ceramic plate is provided on the inner sideof the cooling metal on each side of the semiconductor module, andsemiconductor chips of the upper arm and the lower arm that constitutethe upper and lower arms series circuit are sandwiched between theconductor metals fixed to the respective electric insulation members.With this structure, a good thermal conduction path is establishedbetween the both sides of the semiconductor chips of the upper and thelower arms and the cooling metals, so that the cooling efficiency of thesemiconductor module is greatly improved.

Semiconductor chips (IGBT chips and diode chips) of the upper arm andsemiconductor chips of the lower arm of the semiconductor module arearranged with a shift with respect to a direction of flow of the coolingwater. The IGBT chips of the upper and the IGBT chips of the lower armsare arranged on the same level surface as the flow of the cooling water.These arrangements achieves a vertical width that is appropriated forthe fin-shaped cooling metal to cool the IGBT chips of the upper andlower arms series circuit larger than a vertical width that isappropriated for cooling the diode chips. Thus, the IGBT chips, whichhave larger heat dissipation, are effectively cooled. In other words, alarger amount of the cooling water is assured to cool the IGBT chips ofthe upper and lower arms than to cool the diode chips thereof, therebysignificantly improving the cooling efficiency.

The both sides of each of the semiconductor chips of the upper arms andthe lower arms are connected to respective conductor metals (conductingplates) on the inner side of the cooling metal. The respective conductormetals are fixed to the cooling metal through the electric insulationmember. The insulation member is configured to be thin, with a ceramicplate being 350 μm thin or thinner, and an electric insulating sheetbeing 50 μm to 200 μm thin. The electric insulation sheet includes athermocompressively bonded resin sheet. Since the conductor metal isprovided close to the cooling metal, eddy current is generated due tocurrent flowing in the conductor metal and flows in the cooling metal togenerate heat. The heat thus generated can be efficiently conducted tothe cooling water.

The eddy current decreases the inductance in the semiconductor module.The decrease in the inductance results in a decrease in voltage spikeresults from a switching operation of the semiconductor chips of theupper arms and the lower arms, thereby improving the reliability. Bysuppressing voltage rise, it is possible to perform a faster switchingoperation of the semiconductor chips of the upper arms and the lowerarms, thereby reducing the time for the switching operation and reducingthe amount of heat generated by the switching operation.

The capacitor module and the semiconductor module are contained in achannel case of a substantially same plane. In addition, the capacitormodule is sandwiched between the semiconductor modules. Thus,miniaturization is achieved. Furthermore, a driver board for driving thesemiconductor chips and a control board for controlling thesemiconductor chips are provided on the upper surface of the capacitormodule, so that the upper surface of the capacitor module is effectivelyused, thereby achieving the miniaturization.

(2) Explanation on Improvement of Reliability

As described above, the electric power conversion apparatus according tothe present embodiment significantly improves the cooling efficiency ofthe semiconductor module. This suppresses temperature rise of thesemiconductor chips, thereby improving reliability.

A plurality of the semiconductor modules sandwich the capacitor module.The direct current positive terminals and the direct current negativeterminals of the semiconductor modules are arranged at regular intervalsfrom the capacitor module. This configuration enables these DC terminalsand the positive side terminal and the negative side terminal of thecapacitor module to be connected with each other using uniformly shapeddirect current bus bars. Thus, low inductance between the semiconductormodules and the capacitor module is achieved, while low inductance inthe semiconductor module is realized through the internal configurationof the semiconductor module, thereby reducing voltage spike caused by aswitching operation and improving the reliability. By restrictingvoltage rise, a faster switching operation of the semiconductor chips isenabled, thereby reducing the time for the switching operation andreducing the amount of heat generated by the switching operation. Thisprevents temperature of the semiconductor chips from rising, therebyimproving reliability.

As explained above, the structure with which the DC terminal of thesemiconductor module is connected to the capacitor module and theterminal structure of the capacitor module become simpler. This leadsnot only to improvement of productivity and miniaturization but also toimprovement of the reliability of the semiconductor module.

In the electric power conversion apparatus of the present embodiment,the cooling efficiency is improved to a greater extent so that theengine cooling water can be used as a cooling water. Therefore, theautomobile does not need any dedicated cooling water system and thesystem of the automobile in whole can be made simpler, thus presentingimprovement with high reliability.

The electric power conversion apparatus of the present embodiment isconfigured such that the semiconductor module that houses the seriescircuit of the upper and lower arms of the inverter is inserted in thecooling water channel through an opening provided in the cooling waterchannel and fixed to the cooling water channel. There can be performed aprocess in which the semiconductor module and the channel caseseparately produced in different production lines are separately checkedand then the semiconductor module is fixed to the channel case. In thismanner, the semiconductor module, which is an electric component, andthe channel case, which is a mechanical component, can be separatelyproduced and checked, so that not only improvement of productivity butalso improvement of reliability can be obtained.

It is possible to adopt a method in which a conductor or a semiconductorchip as necessary is fixed to a first and a second heat dissipationmetals and then the first and the second heat dissipation metals areintegrated to produce a semiconductor module. It is possible to performthe process of integrating the heat dissipation metals after the stateof production of the first and the second heat dissipation metals isconfirmed. This leads not only to improvement of productivity but alsoto improvement of reliability of the semiconductor module.

The electric power conversion apparatus according to the presentembodiment is configured such that when the collector surface of thesemiconductor chip of the upper arm is fixed to the first heatdissipation metal, the collector surface of the semiconductor chip ofthe lower arm is fixed to the same first heat dissipation metal, so thatthe collector surface and the emitter surface of the semiconductor chipsof the upper and the lower arms are in the same direction. With thisconfiguration, the productivity and reliability of the semiconductormodule is improved.

The electric power conversion apparatus according to the presentembodiment is configured such that the semiconductor chip of the upperand the lower arms as well as the signal terminals of and the gateterminals of the upper and the lower arms are fixed to the same heatdissipation metal. For this reason, the process of wire bonding toconnect the semiconductor chip with the signal terminal and the gateterminal can be concentrated on one of the heat dissipation metals,which makes it easier to perform the tests. This improves not onlyproductivity but also reliability of the electric power conversionapparatus.

The semiconductor modules of U-phase, V-phase, and W-phase are arrangedon each side of the capacitor module of the sandwich structure in thechannel case. This arrangement reduces the number of U-turn points ofthe cooling water channel, thereby reducing pressure drop in thechannel, lowering source pressure of the cooling water, and controllingcooling water leaks. Thus, reliability is ensured. Moreover, thecapacitor module is disposed in the cooling water channel provided onthe substantially same plane. The inner wall of the channel case and theouter wall of the capacitor module are thermally bonded using thermallyconductive material (resin or grease). This configuration enables thecapacitor module, as well as the semiconductor module, to be directlycooled, stabilizing the performance of these modules and contributing toimprovement in reliability of power conversion device.

(3) Explanation on Improvement of Productivity

As mentioned above, the electric power conversion apparatus according tothe present embodiment may be configured such that the semiconductormodule and the cooling case are separately produced and then a processof fixing the semiconductor modules to the cooling case is performed, sothat the semiconductor modules can be produced on the production linefor an electrical system. This improves the productivity and reliabilityof the electric power conversion apparatus. Also, the capacitor modulecan be separately produced in another production process in the samemanner as above and then fixed to the channel case, so that theproductivity thereof is improved.

The semiconductor module and the capacitor module can be fixed to thechannel case and then the terminals of the semiconductor module and thecapacitor module can be connected to each other. Moreover, a space inwhich a welding machine for the connection is brought to a section to bewelded can be secured. This leads to improvement of the productivity. Inthis connection process, the terminals of the semiconductor module arefixed to the heat dissipation metals, and the heat upon welding theterminals diffuses to the heat dissipation metals, so that adverseinfluences to semiconductor chips can be avoided, resulting inimprovement in the productivity and reliability of the electric powerconversion apparatus.

The semiconductor chip of the upper and the lower arms as well as thesignal terminals of and the gate terminals of the upper and the lowerarms can be fixed to one of the heat dissipation metals of thesemiconductor module, so that wire bonding for both the upper arms andthe lower arms can be performed on the production line of one of theheat dissipation metals. This improves the productivity of the heatconversion device.

The electric power conversion apparatus according to the presentembodiment enables mass production of semiconductor modules of the samestructure and enables a method in which a necessary number ofsemiconductor modules are used based on the specification required forthe electric power conversion apparatus. This makes it possible toperform mass production of standardized semiconductor modules to improvethe productivity, to reduce the cost, and to improve the reliability ofthe semiconductor module. As discussed above, the electric powerconversion apparatus according to the embodiment of the presentinvention is designed to achieve the characteristic structures andeffects based on the three technical viewpoints. The explanation of theelectric power conversion apparatus will be now described.

Embodiment

Now, referring to the attached drawings, the electric power conversionapparatus according to an embodiment of the present invention isdescribed in detail. The electric power conversion apparatus of theembodiment present invention is applicable to hybrid automobiles andpure electric cars. A typical example of control mechanism and circuitryof the electric power conversion apparatus when the electric powerconversion apparatus according to the present embodiment is applied tothe hybrid automobile is described with reference to FIGS. 1 and 2. FIG.1 is a diagram presenting a control block of a hybrid automobile. FIG. 2is a diagram illustrating circuitry of an electric system for driving avehicle that includes an electric power conversion apparatus constitutedof an inverter device having an upper and lower arms series circuit anda capacitor connected to the upstream side of the inverter device, abattery, and a motor generator.

The electric power conversion apparatus according to the embodiment ofthe present invention is described taking as an example of an in-vehicleelectric power conversion apparatus for an in-vehicle electric system tobe mounted on an automobile, in particular an inverter device fordriving a vehicle for use in an electric system for driving a vehicle,which is placed under severe mounting and operating environments. Theinverter device for driving a vehicle is included in an electric systemfor driving a vehicle as a control device that controls driving of arotating electrical machine for driving a vehicle. The inverter deviceconverts direct current power supplied from an in-vehicle battery or anin-vehicle power generation device that constitutes an in-vehicle powersource to predetermined alternate current power and supplies theobtained alternate current power to the rotating electrical machine fordriving the vehicle to control the driving of the rotating electricalmachine. Because the rotating electrical machine also has the functionto serve as a power generation device, the inverter device for drivingthe vehicle has a function to convert the alternate current powergenerated by the rotating electrical machine to direct current power inaccordance with the driving mode. The converted direct current power issupplied to the in-vehicle battery.

While the configuration of the electric power conversion apparatusaccording to the present embodiment is also applicable to inverterdevices to be used other than for driving a vehicle, for instance, aninverter device to be used as a control device for anelectrically-operated braking device or an electrically-operated powersteering device, the electric power conversion apparatus exhibits mostdesirable effect when applied to the inverter device for driving thevehicle. The concept of the electric power conversion apparatus isapplicable to other in-vehicle electric power conversion apparatuses,for example, a DC-DC power conversion device or an AC-DC powerconversion device, such as a DC/DC converter or a DC chopper. However,when applied to an electric power conversion apparatus for driving avehicle, the electric power conversion apparatus according to thepresent embodiment exhibits the most desirable effects. Furthermore, theconcept of the electric power conversion apparatus is applicable to anindustrial electrical power conversion apparatus used as a controldevice for a rotating electrical machine that drives plant facilities,or also applicable to a household electrical power conversion deviceused as a control device for a rotating electrical machine that drives ahousehold photovoltaic power generation system or a household appliance.However, as described above, when applied to an electric powerconversion apparatus for driving a vehicle, the electric powerconversion apparatus according to the present embodiment exhibits themost desirable effects.

Explanation is made on the electric power conversion apparatus accordingto the present embodiment taking as an example in which the electricsystem for driving a vehicle equipped with the inverter device fordriving the vehicle to which the present embodiment is applied ismounted on a hybrid automobile. The hybrid automobile is configured touse an engine, which is an internal combustion engine, and a rotatingelectrical machine for driving a vehicle as driving power sources andeither one of front and rear wheels is driven. Hybrid automobiles may beconfigured such that the engine drives one of the front and rear wheelsand the rotating electrical machine for driving the vehicle drives theother of the front and rear wheels. The present embodiment is applicableto any of the types of the hybrid automobiles. As mentioned above, thepresent embodiment is applicable to pure electric automobiles such as afuel battery car. In the pure electric vehicles, the electric powerconversion apparatus detailed hereinbelow operates substantially in thesame manner and substantially the same effects can be obtained.

Referring to FIG. 1, a hybrid electric vehicle (herein after, referredto as “HEV”) 10 is an electric vehicle that includes two systems fordriving the vehicle. One is an engine system that uses an engine 20,which is an internal combustion engine, as a power source. The enginesystem is used mainly as a driving power source for HEV. The other is anin-vehicle electric system that uses motor generators 92 and 94 as adriving power source. The in-vehicle electric system is used mainly as adriving power source for HEV and an electric power generation source forHEV. The motor generators 92 and 94, which may be, for example,permanent magnet synchronous motors, can operate either as motors orgenerators depending on the operation mode. Accordingly, the device isreferred to as “motor generator”.

In the front part of a vehicle main body, a front axle 14 is rotatablyjournaled. On both ends of the front axle 14 are provided a pair offront wheels 12. On the rear part of the body, a rear axle is rotatablyjournaled (not shown). On the both ends of the rear axle are provided apair of rear wheels. In the HEV according to the present embodiment, aso-called front wheel driving method is adopted. In the front wheeldriving method, a main wheel that is power-driven is the front wheel 12and the trailing wheel is the rear wheel. A reversed driving method,that is, a so-called rear wheel driving method may also be adopted.

In the center of the front wheel shaft 14 is provided a differentialgear (herein after, referred to as “front wheel DEF”) 16. The front axle14 is mechanically connected with an output side of the front wheel DEF16. An input side of the front wheel DEF 16 is mechanically connectedwith an output shaft of a transmission 18. The front wheel DEF 16 is adifferential power transfer mechanism that distributes rotational driveforce transmitted with its speed changed by the transmission 18 to rightand left front axles 14. An input side of the transmission 18 ismechanically connected with an output side of the motor generator 92. Aninput side of the motor generator 92 is mechanically connected with anoutput side of the engine 20 and an output side of the motor generator94 through a power transfer mechanism 22. The motor generators 92 and 94and the power transfer mechanism 22 are housed in a casing of thetransmission 18.

The power transfer mechanism 22 is a differential mechanism thatincludes gears 23 to 30. The gears 25 to 28 are bevel gears. The gears23, 24, 29, and 30 are spur gears. The motive energy of the motorgenerator 92 is directly transmitted to the transmission 18. The shaftof the motor generator 92 is coaxial with the shaft of the gear 29. Withthis configuration, when no drive power is supplied to the motorgenerator 92, the power transmitted to the gear 29 is directlytransmitted to the input side of the transmission 18 without any change.

When the engine 20 operates to drive the gear 23, the motive energy ofthe engine 20 is transmitted from the gear 23 to the gear 24, from thegear 24 to the gears 26 and 28, and then from the gears 26 and 28 to thegear 30, and finally to the gear 29. When the motor generator 94operates to drive the gear 25, the rotation of the motor generator 94 istransmitted from the gear 25 to the gears 26 and 28 and then from thegears 26 and 28 to the gear 30, and finally to the gear 29. The powertransfer mechanism 22 may employ other mechanisms including a planetarygear mechanism in place of the above-mentioned differential mechanism.

The motor generators 92 and 94 are synchronous machines each including arotor with a permanent magnet. The driving of the motor generators 92and 94 is controlled by controlling alternate current supplied toarmature coils of stators by inverter devices 40 and 42, respectively.The inverter devices 40 and 42 are electrically connected with a battery36. Power can be supplied and received between the battery 36 and theinverter devices 40 and 42.

In the present embodiment, there are provided a first motor generatorunit constituted by the motor generator 92 and the inverter device 40and a second motor generator unit constituted by the motor generator 94and the inverter device 42, which are selectively used depending on thedriving situation. That is, assuming that the vehicle is driven throughmotive energy from the engine 20, if the drive torque of the vehicle isto be assisted, the second motor generator unit is actuated as agenerator unit by the motive energy from the engine 20 to generateelectric power, and the first motor generator is actuated as a motorunit by the generated electric power. Similarly, in the case where thevehicle is driven through motive energy from the engine 20, if the speedof the vehicle is to be assisted, the first motor generator unit isactuated as a generator unit by the motive energy of the engine 20 togenerate electric power, and the second motor generator unit is actuatedas a motor unit by the generated electric power.

In the present embodiment, the vehicle can be driven only by the motiveenergy of the motor generator 92 by actuating the first motor generatorunit as a motor unit by the electric power from the battery 36. In thepresent embodiment, the battery 36 can be charged by actuating the firstor the second generator unit as a generator unit by the motive energyfrom the engine 20 or the motive energy from the wheels to perform powergeneration.

Now, referring to FIG. 2, the electric circuit configurations of theinverter devices 40 and 42 are described. In the embodiment shown inFIGS. 1 and 2, explanation is made on a case where the inverter devices40 and 42 are separately constructed. However, as described later onreferring to FIG. 7 and so on, the inverter devices 40 and 42 may behoused in one device. The inverter devices 40 and 42 have the sameconstruction to exhibit the same action and have the same function, andhence explanation is made on the inverter device 40 as a representativeexample.

The electric power conversion apparatus 100 according to the presentembodiment includes the inverter device 40, a capacitor 90, a directcurrent connector 38, and an alternate current connector 88. Theinverter device 40 includes an inverter circuit 44 and a control unit70. The inverter circuit 44 includes a plurality of upper and lower armsseries circuits 50 (in the example shown in FIG. 2, three upper andlower arms series circuits 50, 50, and 50). Each of the upper and lowerarms series circuit 50 includes an IGBT (Insulated Gate type BipolarTransistor) 52 and a diode 56, which operate as an upper arm, and anIGBT 62 and a diode 66, which operate as a lower arm. Each of the upperand lower arms series circuits 50 is configured such that an alternatecurrent power line 86 extends from a neutral point (intermediateelectrode 69) of the upper and lower arms series circuit 50 to the motorgenerator 92 through an AC terminal 59. The control unit 70 includes adriver circuit (incorporated in a driver board) 74 that drives andcontrols the inverter circuit 44 and a control circuit 72 (incorporatedin a control board) that supplies control signals to the driver circuit74 through a signal line 76.

The IGBTs 52 and 62 of the upper arm and the lower arm, respectively,are power semiconductor elements for switching. The IGBTs 52 and 62operate when they receive drive signals output from the control unit 70and convert direct current power supplied from the battery 36 into threephase alternate current power. The converted power is supplied to thearmature coil of the motor generator 92. Also, as mentioned above, theIGBTs 52 and 62 are capable of converting the three phase alternatecurrent power generated by the motor generator 92 into direct currentpower.

The electric power conversion apparatus 100 according to the presentembodiment is constituted with a three-phase bridge circuit. And theupper and lower arms series circuits 50, 50, and 50 each for one ofthree phases are electrically connected in parallel between the positiveside and the negative side of the battery 36. The upper and lower armsseries circuit 50, which is called “arms” herein, includes the powersemiconductor device 52 for switching and the diode 56 on the upper armside as well as the power semiconductor device 62 for switching and thediode 66 on the lower arm side.

In the present embodiment, use of IGBTs (Insulated Gate type BipolarTransistors) 52 and 62 as power semiconductor devices for switching isexemplified. The IGBTs 52 and 62 include collector electrodes 53 and 63,emitter electrodes, gate electrodes (gate electrode terminals 54 and64), and signal emitter electrodes (signal emitter electrode terminals55 and 65). The diodes 56 and 66 are electrically connected to betweenthe collector electrodes 53 and 63 and the emitter electrodes of theIGBT 52 and 62, respectively, as shown in the figure. The diodes 56 and66 include each two electrodes, i.e., cathode and anode. The cathodes ofthe diodes are connected to the collector electrodes of the IGBTs 52 and62 and the anodes of the diodes are electrically connected to theemitter electrodes of the IGBTs 52 and 62, respectively, so that adirection from the emitter electrodes to the collector electrodes of theIGBTs 52 and 62 is set as a forward direction.

The power semiconductor for switching may be a MOSFET (Metal OxideSemiconductor Field Effect Transistor). The MOSFET includes threeelectrodes, i.e., a drain electrode, a source electrode, and a gateelectrode. The MOSFET includes a parasitic diode between the sourceelectrode and the drain electrode such that a direction from the drainelectrode to the source electrode is set as a forward direction. Forthis reason, unlike the IGBT, it is unnecessary to provide a diodeseparately.

There are provided three upper and lower arms series circuit 50. Thethree circuits 50 correspond to respective phases of armature coils ofthe motor generator 92. The three upper and lower arms series circuit50, 50, and 50 form U-phase, V-phase, and W-phase to the motor generator92 through the intermediate electrodes 69, each of which connects theemitter electrode of the IGBT 52 and the collector electrode 63 of theIGBT 62, and the AC terminals 59, respectively. The upper and lower armsseries circuits are electrically connected in parallel to each other.The collector electrode 53 of the upper arm IGBT 52 is electricallyconnected to a capacitor electrode on the positive electrode side of thecapacitor 90 through a positive electrode terminal (P terminal) 57. Theemitter electrode of the lower arm IGBT 62 is electrically connected toa capacitor electrode on the negative electrode side of the capacitor 90through a negative electrode terminal (N terminal) 58. The intermediateelectrode 69, which corresponds to a neutral point of each arm (aconnecting part between the emitter electrode of the upper arm IGBT 52and the collector electrode of the lower arm IGBT 62), is electricallyconnected to a corresponding phase coil among the armature coils of themotor generator 92 through an AC connector 88. In the presentembodiment, as described hereinafter in detail, the single upper andlower arms series circuit 50 constituted by the upper and the lower armsserves as a main circuit component of the semiconductor module.

The capacitor 90 is to constitute a smoothing circuit that suppressesvariation of direct current voltage generated by the switching action ofthe IGBTs 52 and 62. The positive side of the battery 36 is electricallyconnected to the capacitor electrode of the capacitor 90 on the positiveelectrode side through the direct current connector 38. The negativeside of the battery 36 is electrically connected to the capacitorelectrode of the capacitor 90 on the negative electrode side through thedirect current connector 38. With this construction, the capacitor 90 isconnected to between the collector electrode 53 of the upper arm IGBT 52and the positive of the battery 36 and to between the emitter electrodeof the lower arm IGBT 62 and the negative side of the battery 36, sothat the capacitor 90 is electrically connected to the battery 36 andthe upper and lower arms series circuit 50 in parallel.

The control unit 70 is provided in order to actuate the IGBTs 52 and 62.The control unit 70 includes the control circuit 72 (incorporated in thecontrol board) that generates timing signals for controlling switchingtimings of the IGBTs 52 and 62 based on information input from othercontrol unit, a sensor, and so on and the driver circuit 74(incorporated in the driver board) that generates drive signals forcausing the IGBTs 52 and 62 to perform switching action based on thetiming signals output from the control circuit 72.

The control circuit 72 includes a microcomputer that calculatesswitching timing of the IGBTs 52 and 62. To the microcomputer, inputinformation is input, which includes a target torque value required forthe motor generator 92, a value of the current to be supplied to thearmature coils of the motor generator 92 from the upper and lower armsseries circuit 50, and a position of a magnetic pole of the rotor of themotor generator 92. The target torque value is set based on a commandsignal output from a superordinate control unit not shown in the figure.The current value is determined based on the detection signal outputfrom a current sensor 80. The position of magnetic pole is determinedbased on the detection signal output from a rotating magnetic polesensor (not shown) provided in the motor generator 92. In the presentembodiment, explanation is made on an example in which current valuesfor three phases are detected. However, it would also be acceptable thatcurrent values for two phases are detected.

The microcomputer in the control circuit 72 calculates current commandvalues along d and q axes of the motor generator 92 based on the targettorque value, calculates voltage command values along the d and q axesof the motor generator 92 based on differences between the calculatedcurrent command values along the d and q axes and the detected currentvalues along the d and q axes, and converts the calculated voltagecommand values into the voltage command values for U-phase, V-phase, andW-phase based on the detected positions of magnetic pole. Themicrocomputer generates a pulsed modulation wave based on comparisonbetween a fundamental harmonic (sine wave) based on the voltage commandvalues for U-phase, V-phase, and W-phase and a carrier wave (trianglewave), and outputs the generated modulation wave to the driver circuit74 as PWM (Pulse Width Modulated) signals. The microcomputer outputs tothe driver circuit 74 six PWM signals corresponding to the upper and thelower arms for respective phases. The timing signals output from themicrocomputer may be other signals such as square waves.

The driver circuit 74 is constituted by an integrated circuit, so-calleddriver IC, which is obtained by integrating a plurality of electroniccircuit components into one. In the present embodiment, explanation ismade taking an example in which each of the upper arm and lower arm foreach phase is provided with one IC (one arm in one module: one in one).It would also be acceptable to construct the driver circuit 74 such thatone IC is provided so as to correspond to each arm which includes theupper and lower arms for each phase (two in one) or such that one IC isprovided so as to correspond to all the arms (six in one). The drivercircuit 74 amplifies a PWM signal when a lower arm is driven and outputsthe amplified PWM signal as a drive signal to the gate electrode of theIGBT 62 of the corresponding lower arm. When an upper arm is driven, thedriver circuit 74 amplifies a PWM signal after shifting a level of areference potential of the PWM signal to a level of a referencepotential of the upper arm, and outputs the amplified signal as a drivesignal to the gate electrode of the IGBT 52 of the corresponding upperarm. With this, each of the IGBTs 52 and 62 performs a switching actionbased on the input drive signal.

The control unit 70 performs detection of abnormalities (overcurrent,overvoltage, overtemperature, and so on) to protect the upper and lowerarm series circuits 50. For this purpose, sensing information is inputto the control unit 70. For example, information on the current thatflows through the emitter electrode of each of the IGBTs 52 and 62 isinput from the signal emitter electrode terminals 55 and 65 in each armto the corresponding driving unit (IC). With this, each driving unit(IC) performs overcurrent detection and when overcurrent is detected,the driving unit (IC) stops the switching action of the correspondingone of the IGBTs 52 and 62 in order to protect the corresponding one ofthe IGBTs 52 and 62 from the overcurrent. Information on the temperatureof the upper and lower arms series circuit 50 is input from thetemperature sensor (not shown) provided in the upper and lower armsseries circuit 50 into the microcomputer. In addition, information onthe voltage of the direct current positive electrode side of the upperand lower arms series circuit 50 is input to the microcomputer.

The microcomputer performs overtemperature detection and overvoltagedetection based on these pieces of information. When overtemperature orovervoltage is detected, the microcomputer causes the switching actionsof all of the IGBTs 52 and 62 to stop in order to protect the upper andlower arms series circuit 50 (consequently, the semiconductor moduleincluding this circuit 50) from the overtemperature or the overvoltage.

In FIG. 2, the upper and lower arms series circuit 50 is a seriescircuit constituted by the IGBT 52 of the upper arm, the diode 56 of theupper arm, the IGBT 62 of the lower arm, and the diode 66 of the lowerarm. The IGBTs 52 and 62 are semiconductor elements for switching.Conduction and blocking actions of the IGBTs 52 and 62 of the upper andthe lower arms in the inverter circuit 44 are switched in apredetermined order and the current of the stator coil of the motorgenerator 92 upon the switching flows in a circuit formed by the diodes56 and 66.

The upper and lower arms series circuit 50, as shown, includes thepositive terminal (P terminal) 57, the negative terminal (N terminal)58, the AC terminal 59 (see FIG. 3) from the intermediate electrode 69of the upper and the lower arms, the signal terminal (signal emitterelectrode terminal) 55 of the upper arm, the gate (base) electrodeterminal 54 of the upper arm, the signal terminal (signal emitterelectrode terminal) 65 of the lower arm, and the gate (base) electrodeterminal 64 of the lower arm. The electric power conversion apparatus100 includes the direct current connector 38 on the input side and thealternate current connector 88 on the output side and is electricallyconnected to the battery 36 and the motor generator 92 through theconnectors 38 and 88, respectively.

FIG. 3 is a diagram that shows circuitry of an electric power conversionapparatus in which two upper and lower arms series circuits are providedfor each phase as a circuit that generates output of each phase of thethree-phase alternate current to be output to the motor generator. Whenthe capacity of the motor generator is increased, electric energyconverted by the electric power conversion apparatus increases, and thevalue of the current that flows in the upper and lower arms seriescircuit for each phase of the inverter circuit 44 increases. Theincrease in power to be converted can be coped with by increasing theelectrical capacity of the upper and lower arms. However, it ispreferred that the quantity of output of inverter circuits (invertermodules) is increased. The configuration shown in FIG. 3 is intended tocope with the increase in the electric energy to be converted byincreasing the number of inverter circuits (modules) used that areproduced in a standardized fashion.

While the inverter circuit 44 shown in FIG. 2 includes the three upperand lower arms series circuits 50, 50, and 50 so as to form U-phase,V-phase, and W-phase to the motor generator 92, the configuration shownin FIG. 3 includes two parallelly connected inverter circuits, that is,a first inverter circuit 45 and a second inverter circuit 46, which havethe same configuration as the inverter circuit 44 shown in FIG. 2 has,so as to cope with the increase in the capacity of the motor generator92 to be controlled. The configuration shown in FIG. 3 includes upperand lower arms series circuits 50U1 and 50U2 corresponding to theU-phase of the upper and lower arms series circuit 50 shown in FIG. 2,upper and lower arms series circuits 50V1 and 50V2 for the V-phase, andupper and lower arms series circuits 50W1 and 50W2 for the W-phase. Itshould be noted that alternate current power lines 86 of the first andsecond inverter circuits shown in FIG. 3 are represented by a firstalternate current bus bar 391 and a second alternate current bus bar 392in the drawings hereinafter.

An overall configuration of the electric power conversion apparatusaccording to the embodiment of the present invention will now bedescribed. FIG. 4 is a perspective view showing an appearanceconfiguration of the electric power conversion apparatus according tothe embodiment of the present invention. FIG. 5 is an explodedperspective view of the electric power conversion apparatus according tothe embodiment of the present invention. FIG. 6 is a plan view of theelectric power conversion apparatus according to the embodiment of thepresent invention without the upper case.

FIGS. 4 to 6 show a specific example of the electric power conversionapparatus according to the present embodiment with a circuit constitutedby the first inverter circuit 45 and the second inverter circuit 46shown in FIG. 3. Reference numeral 38 designates a direct currentconnector; 88 designates a first alternate current connector (aconnector that is connected to the alternate current power line 86 ofthe first inverter circuit shown in FIG. 3); 89 designates a secondalternate current connector (a connector of the electric powerconversion apparatus that is connected to the alternate current powerline 86 of the second inverter circuit shown in FIG. 3); 91 designatesan alternate current connector flange; 100 designates the electric powerconversion apparatus; 112 designates the upper case; 122 designates apositioning member for the alternate current connectors; 124 designatesa flange of the upper case; 142 designates a lower case; 144 designatesa water channel lid; 145 designates a first module lid; 146 designates asecond module lid; 246 designates a water channel inlet; 248 designatesa water channel outlet; 372 designates a control board (the controlcircuit is incorporated therein); 373 designates a first control IC; 374designates a second control IC; 386 designates a driver board; 387designates a driver IC; 388 designates a signal connector; 391designates the first alternate current bus bar (the alternate currentpower line 86 of the first inverter circuits shown in FIG. 3); and, 392designates the second alternate current bus bar 2 (the alternate currentpower line 86 of the second inverter circuits shown in FIG. 3).

For external electrical connection, the electric power conversionapparatus 100 according to the embodiment of the present invention shownin FIGS. 4 to 6 includes the direct current connector 38 that connectswith the battery 36 (see FIG. 2), the first alternate current connector88 and the second alternate current connector 89 that connect with themotor generator 92 (see FIG. 2). An appearance configuration of theelectric power conversion apparatus 100 according to the embodiment ofthe present invention shown in FIGS. 4 to 6 includes the upper case 112,the lower case 142, and the water channel inlet 246 and the waterchannel outlet 248 through which the cooling water is taken in or outfor cooling the semiconductor module including the upper and lower armsseries circuit 50 and the capacitor module.

The control board 372 and the driver board 386 are placed one on top ofthe other (see FIG. 5) between the upper case 112, and the first modulelid 145 and the second module lid 146. The first module lid 145 coverseach of the semiconductor modules including the upper and lower armsseries circuit for each of U1 phase, V1 phase, and W1 phase shown inFIG. 3. The second module lid 146 covers each of the semiconductormodules including the upper and lower arms series circuit for each of U2phase, V2 phase, and W2 phase shown in FIG. 3. The control board 372 ismounted with the first control IC 373 and the second control IC 374. Thedriver board 386 is mounted with the driver ICs 387. The first alternatecurrent bus bars 391 and the second alternate current bus bar 392 areprovided in a lower part of the driver board 386 for three phases. Asdescribed later, the semiconductor module including the upper and lowerarms series circuit 50 and the fin is loaded in the horizontally formedwater channel space including the water channel inlet 246 and the waterchannel outlet 248.

A semiconductor module 500 of the electric power conversion apparatusaccording to the embodiment of the present invention will now bedescribed with reference to FIGS. 13 to 16. FIG. 13 is a perspectiveview showing the semiconductor module of the electric power conversionapparatus according to the embodiment of the present invention. FIG. 14is a sectional view taken through A-A line (shown in FIG. 13) of thesemiconductor module according to the present embodiment. FIG. 15 is anexploded perspective view of the semiconductor module according to thepresent embodiment. FIG. 16 is a sectional view taken through B-B line(shown in FIG. 15) of the semiconductor module according to the presentembodiment.

In FIGS. 13 to 16, the semiconductor module 500 of the electric powerconversion apparatus according to the embodiment of the presentinvention includes a n fin 522 on one side (side A) 522, a fin 562 onanother side (side B), the upper and lower arms series circuit 50sandwiched by the fins 522 and 562, various terminals including apositive terminal 532, a negative terminal 572 and an alternate currentterminal 582, a top case 512, a bottom case 516, and a side case 508. Itis to be noted that a fin refers to not only a fin-shaped part havingprotrusion and depression but also a heat dissipation metal in whole. Asshown in FIGS. 14 and 15, the semiconductor module 500 is obtained as anintegrated structure as follows. The upper and lower arms seriescircuits (whose production method is described later on) are provided onconducting plates that are fixed to the fin (side A) 522 and the fin(side B) 562 through electric insulation sheets, respectively. In astate in which the upper and lower arms series circuits are sandwichedby the fin (side A) 522 and the fin (side B) 562 therebetween, thebottom case 516, the top case 512, and the side case 508 are assembledtogether. Then a mold resin is filled between the fins 522 and 562 fromthe side of the top case 512 to obtain an integrated structure.

The semiconductor module 500 has an appearance as shown in FIG. 13. Thatis, the fin (side A) 522 and the fin (side B) 562 are formed so as to beexposed to or inserted into the cooling water channel. Through the topcase 512, there protrude the positive terminal 532 (corresponding to theP terminal 57 in FIGS. 2 and 3), the negative terminal 572(corresponding to the N terminal 58 in FIGS. 2 and 3), the AC terminal582 (corresponding to the AC terminal 59 in FIG. 3), the signal terminal552 (for the upper arm), the gate terminal 553 (for the upper arm), thesignal terminal 556 (for the lower arm), and the gate terminal 557 (forthe lower arm) of the upper and lower arms series circuit 50.

The appearance configuration of the semiconductor module 500 issubstantially rectangular parallelepiped. The fin (side A) 522 and thefin (side B) 562 both have a large area. Assuming that the face of thefin (side B) 562 is a front face and the face of the fin (side A) is arear face (as shown in FIG. 13), both of the sides, i.e., the side atwhich the side case 508 is depicted and the side opposite thereto, aswell as the bottom face and the top face have areas smaller than that ofthe above-mentioned front face or the rear face. Since the basic shapeof the semiconductor module is substantially rectangular parallelepipedand the fin (side B) 562 and the fin (side A) 522 are rectangular, theircutting work is easy. In addition, due to its shape, the semiconductormodule is less likely to turn over in the production line, achievingexcellent productivity. Moreover, a ratio of heat dissipation area tothe whole volume can be made large, improving the cooling effect.

In the present embodiment, each of the fin (side A) 522 and the fin(side B) 562 is configured with a metal plate to be used to sandwich thesemiconductor chip and hold the conductor in the semiconductor moduleand the fin that dissipates heat, and the metal plate and the fine aremade of a single metal material. This structure is excellent inincreasing the heat dissipation efficiency of the semiconductor module.Another structure with slightly less heat dissipation efficiency mayalso be used: a metal plate to be used to sandwich the semiconductorchip and hold the conductor in the semiconductor module and the fin thatdissipates heat may be made separately and affixed together.

On the top face, which is one of smaller faces of the substantiallyrectangular parallelepiped, there are assembled the positive terminal532 (corresponding to the P terminal 57 in FIG. 3), the negativeterminal 572 (corresponding to the N terminal 58 in FIG. 3), the ACterminal 582 (corresponding to the AC terminal 59 in FIG. 3), the signalterminal 552 (for the upper arm), the gate terminal 553 (for the upperarm), the signal terminal 556 (for the lower arm), and the gate terminal557 (for the lower arm). This structure is excellent in easily insertingthe semiconductor module 500 into the water channel case. A hole 583 isprovided between the positive terminal 532 and the negative terminal 572to assure insulation therebetween. More specifically, the hole 583 isformed in a mold resin 507 between the positive terminal 532 and thenegative terminal 572. As described later, a terminal insulation partattached to the capacitor module which is provided between the positiveterminal and the negative terminal of the capacitor module 390 isinserted into the hole 583 (see FIG. 21). The hole 583 thus functionsboth as insulation between the terminals and as positioning.

The area of the top face on which the above-mentioned terminals areprovided is made larger than the area of the bottom face, as shown inFIG. 13, so as to protect the terminal parts that otherwise tend to bedamaged as the semiconductor module is moved on the production line orthe like. That is, the area of the top case 512 is made larger than thearea of the bottom case 516, so as to provide excellent sealability ofthe opening of the cooling water channel which is to be describedhereinbelow, as well as to protect the terminals of the semiconductormodule when the semiconductor module is produced, transported, andattached to the channel case.

With the arrange of the terminals shown in FIG. 13, the positiveterminal 532 and the negative terminal 572 each have a plate-likerectangular cross-section and a comb-like tip. The positive terminal 532and the negative terminal 572 are arranged right and left at equalspaces seen from the fin (side B) 562, and arranged close to one side ofthe semiconductor module. As shown in FIGS. 13 and 14, the terminals 532and 572 each include the conductor plate of the arm that extends in avertical direction (set up vertically) and thereafter extends in ahorizontal direction (bent at a right angle) up to the comb-like tip. Inother words, the positive terminal 532 and the negative terminal 572include bends and the comb-like tips are arranged along the fin 522(side A). While the terminals 532 and 572 shown in FIGS. 13 and 14include the bends, the terminals 532 and 572 shown in FIGS. 15 to 20 donot include the bends and are straight. This is because FIG. 13 showsthe terminals after being bent while FIGS. 15 to 20 show the terminalsbefore being bent. The terminals are bent after process of soldering,inner molding, and case adhering (joining) so that a force is notapplied on the inside semiconductor and the soldering part at the timeof the bending. Additionally, assembly of the top case 512 becomesdifficult after terminals are bent.

As described in detail later, since the capacitor module 390 is arrangedfacing the fin (side B) 562, the positive electrode terminal and thenegative electrode terminal of the capacitor module are connected withthe positive electrode terminal 532 and the negative electrode terminal572 of the semiconductor module through DC bus bars of equal length toeach other, respectively. This makes wiring easy. Connecting ends of thepositive electrode terminal 532 and the negative electrode terminal 572are each arranged with a shift from a connecting end of the AC terminal582 in the front and rear direction of the semiconductor module(direction connecting both sides of the semiconductor module to eachother). This ensures a space for using a tool for connecting theconnecting ends of the positive electrode terminal 532 and of thenegative electrode terminal 572 to other components as well as forconnecting the connecting end of the AC terminal 582 to othercomponents, achieving excellent productivity.

There is a possibility that an electric power conversion apparatus foran automobile is cooled down to −30° C. or lower, even as low as around−40° C. On the other hand, there is a possibility that the temperatureof the electric power conversion apparatus reaches 100° C. or higher,infrequently as high as around 150° C. As mentioned above, the electricpower conversion apparatus to be mounted on an automobile is used attemperatures in a wide range and hence it is necessary to give dueconsiderations to changes due to thermal expansion. The electric powerconversion apparatus is also used in an environment in which vibrationis always applied thereto. The semiconductor module 500 described withreference to FIGS. 13 to 16 has a structure in which the semiconductorchip is sandwiched by two heat dissipation metals. According to thisembodiment, a metal plate having fins with excellent heat dissipationfunction is used as an example of a heat dissipation metal. This isdescribed in the present embodiment as the fin 522 (side A) and the fin562 (side B).

In the above-mentioned structure of sandwiching the semiconductor chip,both sides of the two heat dissipation metals are fixed with the topcase 512 and the bottom case 516. In particular, the top case 512 andthe bottom case 516 each sandwich the two heat dissipation metals fromthe outer sides thereof. Specifically, it is only necessary to fitprotrusions of the two heat dissipation metals 522 and 562 in fittingparts 517 of the bottom case 516. It is only necessary to apply the samefitting structure to the top case 512. This structure prevents a largeforce from generating in the direction in which the two heat dissipationmetals move away from each other due to vibration and thermal expansion,thereby achieving a highly reliable electric power conversion apparatuswithout malfunction even through a long-term use mounted on anautomobile.

In the present embodiment, a structure is adopted in which the top case512 and the bottom case 516 sandwich the above-mentioned two heatdissipation metals as well as the side cases so as to enclose the heatdissipation metals and fix them from the outer circumferential sides.Accordingly, the reliability of the electric power conversion apparatusis further increased.

The positive electrode terminal 532, the negative electrode terminal572, the AC terminal 582, the signal terminals 552 and 556, and the gateterminals 553 and 557 of the semiconductor module are configured toprotrude to outside through an opening in the top case 512, which is oneof the cases. The opening is sealed with the mold resin 507. The topcase 512 is made of a material having high strength, for example, ametal, which has the thermal expansion coefficient close to that of thetwo heat dissipation metals. The mold resin 507 absorbs stress generatedby thermal expansion of the case 512 and reduces the stress applied tothe above-mentioned terminals. Therefore, the electric power conversionapparatus according to the present embodiment can be used in anenvironment with severe temperature changes or with constant vibrationapplied thereto. High reliability is thus assured.

FIG. 17 is an exploded diagram showing a perspective view of theinternal configuration of an upper and lower arms series circuit of thesemiconductor module according to the present embodiment. Thesemiconductor module according to the present embodiment shown in FIG.17 is produced in the following order. Plates of heat dissipation metal,for example, the fin (side A) 522 and the fin (side B) 562, which aremetal plates with fin structure, are used as basis materials, and anelectric insulation sheet (side A) 546 and an electric insulation sheet(side B) 596 are fixed to the inner sides of the metal plates,respectively, by vacuum thermocompression. A conducting plate 534 on thepositive electrode side and an upper and lower arms connectionconducting plate 535 are fixed to the electric insulation sheet (side A)546 (see FIG. 19). A conducting plate 574 on the negative electrode sideand a conducting plate 584 on the AC terminal side are fixed to theelectric insulation sheet (side B) 596. The signal terminal 556 for thelower arm is connected to the conducting plate 574 on the negativeelectrode side. The signal terminal 552 for the upper arm is connectedto the conducting plate 584 on the AC terminal side (see FIG. 20).

The electric insulation sheet (side A) 546 and the electric insulationsheet (side B) 596 are explained below. They function as insulationmembers that electrically insulate the semiconductor chip and conductorsconstituting the upper and lower arms series circuit of the invertercircuit from the fin (side A) 522 and the fin (side B) 562. They alsoserve to form a heat conducting path that conducts heat generated by thesemiconductor chip and so on to the fin (side A) 522 and the fin (sideB) 562. The insulation member may be an electric insulation sheet orplate made of a resin or may be a ceramic board. For example, theinsulation member of a ceramic board is preferably 350 μm thick orthinner. The insulation member of an electric insulation sheet is eventhinner, preferably between 50 μm to 200 μm thick. It should be notedthat a thinner insulation member is more effective for reducinginductance, therefore an electric insulation sheet made of a resin hasmore excellent characteristics than a ceramic board has.

An upper arm IGBT chip 537 and an upper arm diode chip 539 are arrangedalong a vertical direction and soldered on to the conducting plate 534of the positive electrode side on the fin (side A) 522. Similarly, alower arm IGBT chip 541 and a lower arm diode chip 543 are arrangedalong a vertical direction and soldered on to the upper and lower armsconnection conducting plate 535 on the fin (side A) 522. The size of theIGBT chip measured along the vertical direction is substantially largerthan that of the diode chip. Assuming that a water channel occupancyrepresents a proportion that an IGBT chip and a diode chip occupy to thecooling water flowing through the fin 522, a water channel occupancy ofthe upper arm IGBT chip 537 is larger than that of the upper arm diodechip 539. This facilitates heat dissipation of the IGBT chip, whose heatdissipation amount is larger than that of the diode chip, therebyimproving cooling efficiency of the overall semiconductor module. Thecooling efficiency of the lower arm chips 541 and 543 is improvedsimilarly to that of the upper arm chips.

As further detailed in FIGS. 18 to 20, an upper and lower armsconnection soldered portion 555, which connects the emitter of the upperarm with the collector of the lower arm, similar to the lower arm chips541 and 543, is formed on a conducting plate 535 of the fin (side A) 522(see FIGS. 18 and 19). The soldered portion 555 is connected with the ACterminal 582 (corresponding to the AC terminal 59 in FIG. 3) through asolder layer 544 and the conducting plate 584, constituting theintermediate electrode 69 (see FIG. 2) of the upper and lower armsseries circuit. Wire bondings 593 and 597 respectively connect betweenthe gate electrode of the IGBT 537 of the upper arm and a signalconductor of the gate terminal (for the upper arm) 553 and between thegate electrode of the IGBT 541 of the lower arm and a gate conductor ofthe gate terminal (for the lower arm) 557, soldered on the conductingplates on the fin (side A) 522.

On the other hand, as shown in FIGS. 17 and 20, the electric insulationsheet (side B) 596 of the fin (side B) 562 is fixed with the conductingplate 574 on the negative electrode side of the negative terminal 572,the conducting plate 584 on the AC terminal side of the AC terminal 582,and the conducting plates of each of the signal terminal (for the upperarm) 552 and the signal terminal (for the lower arm) 556. The conductingplate 574 on the negative electrode side is provided with a solderedportion 757 to which the emitter side of the lower arm IGBT chip 541 isconnected and a soldered portion 759 to which the anode side of thelower arm diode chip 543 is connected. The conducting plate 584 on theAC terminal side is provided with a soldered portion 756 to which theemitter side of the upper arm IGBT chip 537 is connected and a solderedportion 758 to which the anode side of the upper arm diode chip 539 isconnected. The negative terminal 572 (corresponding to the negativeterminal 58 in FIG. 2) is connected and fixed to the lower arm IGBT chip541 and the lower arm diode chip 543 through the conducting plate 574,the soldered portions 757 and 759, and solder layers 540 and 542. Thepositive terminal 532 is connected and fixed to the upper arm IGBT chip537 and the upper arm diode chip 539 through the conducting plate 534,soldered portions 751 and 752, and solder layers 536 and 538. The ACterminal 582 is connected and fixed to the lower arm IGBT chip 541through the conducting plate 584, an upper and lower arms connectionsoldered portion 760 connecting to the emitter side of the upper armIGBT chip, the solder layer 544, the upper and lower arms connectionsoldered portion 555, and the conducting plate 535. Each of theconducting plates of the upper arm signal terminal 552 (corresponding tothe signal terminal 55 shown in FIG. 2) and the lower arm signalterminal 556 (corresponding to the signal terminal 65 shown in FIG. 2)is connected to the emitter side of each of the upper arm IGBT chip 537and the lower arm IGBT chip 541. The above-mentioned arrangement for thesemiconductor module constitutes the circuitry of the upper and lowerarms series circuit 50 shown in FIG. 2.

As shown in FIG. 17, a set of the semiconductor chips for the upper armand a set of the semiconductor chips for the lower arm are each arrangedalong the vertical direction and fixed to the fin (side A) 522, which isone of the fins. The fin (side A) 522 is provided with the upper armgate terminal 553 and the lower arm gate terminal 557. This enablesconnecting operation such as wire bonding to be completed intensively inthe production process of one of the fins, i.e., the fin (side A) 522,thereby improving productivity and reliability. Since the semiconductorchip to be wired and the terminal are fixed to the same fin, bettervibration resistance is obtained when the electric power conversionapparatus is used in an environment with large vibration such as anautomobile.

As described above, the fin (side A) 522 and the fin (side B) 562 areplaced facing each other as shown in FIG. 17. The electrodes of the IGBTchips 537 and 541 and the diode chips 539 and 543 of the fin (side A)522 are each faced and soldered to the conducting plates each connectingto the negative terminal 572, the AC terminal 582, the signal terminal552 for the upper arm, and the signal terminal 556 for the lower arm ofthe fin (side B) 562 so as to achieve the circuitry as shown in FIG. 2.As FIG. 15 shows, the bottom case 516, the top case 512, and the sidecases 508 are bonded with an adhesive to the fin (side A) 522 and thefin (side B) 562 constituting an integrated structure. The mold resin isfilled through the opening 513 (see FIG. 15) in the top case into theinside to form the semiconductor module 500.

The production method and structure of the upper and lower arms seriescircuit (for example, 2 arms in 1 module structure) sandwiched betweenboth the fins 522 and 562 of the semiconductor module 500 according tothe present embodiment will now be described with reference to FIGS. 18to 20. FIG. 18 is a perspective view of the upper and lower arms seriescircuit that is disposed in a fin (side A) of the semiconductor moduleaccording to the present embodiment. FIG. 19 is a perspective viewillustrating the connection of components to be disposed in the fin(side A) of the semiconductor module. FIG. 20 is a perspective viewillustrating the connection of components to be disposed in a fin (sideB) of the semiconductor module.

The basic process for producing the semiconductor module according tothe present embodiment will now be described in order. Plates of heatdissipation metal, for example, the fin (side A) 522 and the fin (sideB) 562, which are metal plates with a fin structure in the presentembodiment, are used as base materials, and the electric insulationsheet (side A) 546 and the electric insulation sheet (side B) 596 arefixed to the inner sides thereof by vacuum thermocompression. Theconducting plate 534 and the conducting plate 535 on the positiveelectrode side are fixed to the electric insulation sheet 546 (side A).The conducting plate 574 and the conducting plate 584 for AC terminal onthe negative electrode side are fixed to the electric insulation sheet596 (side B). FIG. 19 shows the fixing of the conducting plates 534 and535 to the fin (side A) 522 and the electric insulation sheet (side A)546. FIG. 20 shows the fixing of the conducting plates 574 and 584 tothe fin (side B) 562 and the electric insulation sheet (side B) 596.

The electric insulation sheet 546 (side A) is fixed with a gateconductor of the gate terminal (for the upper arm) 553 and a gateconductor of the gate terminal (for the lower arm) 557. The electricinsulation sheet 596 (side B) is fixed with a signal conductor of thesignal terminal (for the upper arm) 552 and a signal conductor of thesignal terminal (for the lower arm) 556. The layout of these is as shownin FIGS. 19 and 20.

The IGBT chip 537 (for the upper arm), the diode chip 539 (for the upperarm), the IGBT chip 541 (for the lower arm), and the diode chip 543 (forthe lower arm) are respectively soldered on to the soldered portions751, 752, 753, and 754 provided on the conducting plate 534 and theupper and lower arms connection conducting plate 535 on the positiveelectrode side of the fin (side A) 522 through the solder layers 547,548, 549, and 550. On this occasion, the conducting plate 534 and theconducting plate 535 are provided as insulated from each other, and apair of the IGBT chip and the diode chip are soldered to each of theconducting plates 534 and 535. The soldered portion 555 that connectsthe emitter of the upper arm with the collector of the lower arm asshown in FIG. 2, is soldered to the conducting plate 535 in the samemanner as the chips 541 and 543. The soldered portion 555 for the upperand lower arms connection (see FIG. 19) abuts against and is connectedto the conducting plate 584 for the AC terminal through the upper andlower arms connection soldering part 760 (see FIG. 20) so as toconstitute the intermediate electrode 69 (see FIG. 2).

The gate wire (for the upper arm) 593 is used for bonding connectionbetween the gate electrode of the IGBT 537 of the upper arm soldered onthe conducting plate 534 of the fin (side A) 522 and the gate conductorof the gate terminal (for the upper arm) 553 (see FIG. 17). Likewise,the gate wire (for the lower arm) 597 is used for bonding connectionbetween the gate electrode of the IGBT 541 of the lower arm soldered onthe conducting plate 535 of the fin (side A) 522 and the gate conductorof the gate terminal (for the lower arm) 557 (see FIG. 17).

As shown in FIG. 18, the semiconductor chips for the upper arm and thesemiconductor chips for the lower arm are fixed to the fin (side A) 522,which is one of the fins. The semiconductor chips are provided with thegate conductors that are connected to the gate terminals 553 and 557that control signals. The semiconductor chips for the upper and thelower arms and control lines therefor are thus fixed on one of theinsulation members. This results in intensive production process forconnecting signal lines with the semiconductor chips, such as wirebonding. This also results in improvement in productivity andreliability. Both of the semiconductor chip to be wired and the controlline for wiring are fixed to a single member, that is, one of the fins.Therefore, better vibration resistance is obtained when the electricpower conversion apparatus is used in an environment with largevibration such as an automobile.

As shown in FIG. 19, the semiconductor chip 537 (to be connected to thesoldered portion 751) for the upper arm and the semiconductor chip 541(to be connected to the soldered portion 753) for the lower arm areprovided so as to face toward the same direction. That is, therespective collector surfaces of the semiconductor chips are provided toface the electric insulation sheet 546, which is an insulating member.The soldered portions 751 and 753 are provided to face the collectorsides of the IGBT chips 537 and 541. This alignment of the direction ofthe semiconductor chips of the upper and the lower arms improvesworkability. This is true also for the diode chips 539 and 543.

As shown in FIG. 14, also referring to FIG. 17, the IGBT 52 of the upperarm is provided above the diode 56 of the upper arm in the upper andlower arms series circuit 50 incorporated in the semiconductor module500 according to the present embodiment. This configuration is true forthe IGBT and diode in the lower arm. As detailed later, thesemiconductor module 500 shown in FIG. 13 is inserted into the coolingwater channel from above so that the cooling water flowing in thecooling water channel cools the semiconductor module 500. Morespecifically, the cooling water flows through the comb-like parts(concave, depression part) of the fin (side A) 522 and the fin (side B)562.

The length L of the IGBT 52 is larger than the length M of the diode 56in, for example, the upper arm (L>M). Cooling effect of the coolingwater flowing through the comb-like parts of the fins depends on thelengths L and M. In other words, the amount of the cooling watercorresponds to the lengths L and M. Therefore, the amount of coolingwater used for cooling the IGBT, whose heat should be dissipated morethan that of the diode, is larger than that for the diode, improving thecooling efficiency.

The semiconductor module 500 with the integrated structure shown in FIG.13 includes the positive terminal 532 and the negative terminal 572 thatprotrude upwards, which are to be connected to the positive electrodeside and the negative electrode side of the capacitor 90. The terminals532 and 572 are arranged on a straight line along the cooling waterchannel (along the long side of the rectangle of the cross-section ofthe semiconductor module seen from above). As described in detail later,a plurality of semiconductor modules are provided on the both sides ofthe capacitor module so that the long side of the rectangle of thecross-section of each of the semiconductor modules are substantiallyaligned if seen from above (along the flow of the cooling water). Inother words, the plurality of semiconductor modules sandwich thecapacitor module (see FIG. 11).

In the arrangement of the semiconductor modules and the capacitor moduledescribed above, the terminals on the positive and negative sides of thecapacitor module are arranged so as to face respectively the positiveterminal 532 and the negative terminal 572 of the semiconductor moduleshown in FIG. 13. This enables bars identical in shape and in length tobe used on both the positive and negative sides for connecting thesemiconductor module 500 with the capacitor module 390. This results inimprovement in workability and reduction in inductance which resultsfrom the switching action of the IGBTs.

A specific configuration for improvement in miniaturization, coolingefficiency, and assemblability in the electric power conversionapparatus according to the embodiment of the present invention will nowbe described with reference to FIGS. 7 to 12. FIG. 7 is an explodedperspective view illustrating the arrangement of the semiconductormodules of the electric power conversion apparatus according to theembodiment of the present invention, showing the same electric powerconversion apparatus as that shown in FIG. 5 except for the upper case,the control board, the driver board, and the AC connectors, which havebeen removed therefrom. FIG. 8 is a perspective view of an electricsystem of the semiconductor module shown in FIG. 7 with alternatecurrent connectors and a direct current connector added thereto. FIG. 9is an exploded perspective view of the power system of the semiconductormodule shown in FIG. 8. FIG. 10 is an exploded cross-sectional viewshowing the configuration of the semiconductor module shown in FIG. 7 asseen from the direction of flow of the cooling water. FIG. 11 iscross-sectional view of the electric power conversion apparatusaccording to the present embodiment from which the upper case has beenremoved as seen from the direction of flow of the cooling water. FIG. 12is a cross-sectional view of the semiconductor module, the capacitormodule, and the cooling water channel according to the presentembodiment as seen from above.

Now, arrangement of the semiconductor module, the cooling water channel,and the electric system of the electric power conversion apparatusaccording to the present embodiment will first be described withreference to FIGS. 7 to 9. FIGS. 7 to 9 show examples of the structureof six semiconductor modules of two systems: A first semiconductormodule incorporated therein the upper and lower arms series circuits ofan upper side for U1-phase, V1-phase, and W1-phase as shown in FIG. 3,and a second semiconductor module incorporated therein the upper andlower arms series circuits of a lower side for U2-phase, V2-phase, andW2-phase. The first semiconductor module is connected to the firstalternate current connector 88 through three first alternate current busbars 391. Similarly, the second semiconductor module is connected to thesecond alternate current connector 89 through three second alternatecurrent bus bars 392. In the drawings, the first semiconductor moduleincorporated therein the upper and lower arms series circuits of theupper side for U1-phase, V1-phase, and W1-phase as shown in FIG. 3 isprovided on the side of the cooling water channel inlet 246 (the sidewhere the alternate current connectors 88 and 89 are provided). Thesecond semiconductor module 2 constituted by U2-phase, V2-phase, andW2-phase is provided on the other side (the side of the water channeloutlet 248).

The direct current connector 38 to be connected with the capacitormodule 390 is provided on the opposite side of the side on which thecooling water inlet 246 and the outlet 248 are provided. The alternatecurrent connectors 88 and 89 (see FIG. 3) are mounted on an alternatecurrent connector mounting part 123 sandwiching the positioning member122 for the alternate current connectors, and the alternate currentconnector flange 91 is provided thereon. On the both sides of acapacitor module insertion part (second opening) 147 into which thecapacitor module 390 (see FIG. 11) is inserted, a semiconductor moduleinsertion water channel (first opening) 237 into which the semiconductormodule 500 is inserted is formed in the lower case 142 (see FIG. 10). Athermal conduction material 600 is filled in a gap between the innerwall of the capacitor module insertion part 147 and the outer wallsurface of the capacitor module 390. The thermal conduction material 600includes resin, grease, or the like. The semiconductor modules 500 arethus arranged both sides of the capacitor module 390 so as to sandwichthe capacitor module 390.

The first module lid 145 is provided on the first semiconductor modulearranged on the alternate current connector side. The second module lid146 is provided on the second semiconductor module arranged on theopposite side of the alternate current connector side. The water channellid 144 (see FIG. 9) is provided on a front return channel 227 (seeFIGS. 7 and 12) in which the water channel inlet 246 and the outlet 248are provided. In the semiconductor module insertion water channel 237(see FIG. 10), a rear return channel 236 is provided (see FIG. 7) on theopposite side of the above-mentioned front return channel. A first waterchannel forming member 490 and a second water channel forming member 491are provided near the water channel inlet 246 and near the water channeloutlet 248, respectively, so that the cooling water is guided to flowthroughout the fin (side A) and the fin (side B) of the semiconductormodule (see FIG. 12).

Arrangement of the semiconductor modules, the cooling water channel, andthe electric system of the electric power conversion apparatus accordingto the present embodiment will then be described with reference to FIGS.10 to 12. According to the present embodiment, a slot-in structure isadopted to insert the semiconductor module 500 from above into the waterchannel 237 formed in the lower case 142. The semiconductor module 500is positioned by semiconductor module positioning members 502 of thelower case 142 and is fixed to the water channel 237 by a semiconductormodule fixing member 501 of the module lids 145 and 146.

The semiconductor modules 500, 500, and 500 for U1-phase, V1-phase, andW1-phase shown in FIG. 3, which are arranged along a direction rearwardfrom the first water channel forming member 490, are inserted and fixedto the water channel on the side of the alternate current connectormounting part 123, on which the alternate current connectors 88 and 89are mounted. Likewise, the semiconductor modules 500, 500, and 500 forU2-phase, V2-phase, and W2-phase shown in FIG. 3 are inserted and fixedto the water channel on the side of the water channel outlet 248.

As shown in FIG. 12, the water enters from the water channel inlet 246,as represented by a water flow 250, and guided by the first waterchannel forming member 490. Flow of water, as represented by a waterflow 251, is generated along the side of one of the fins of thesemiconductor module 500. The water passes through or is bent throughthe return channel 236 in the rear section of the water channel 237 asindicated by a water flow 252, to create a water flow 253. Then, thewater is guided by the first water channel forming member 490 to flowthrough the front return channel 227, and is guided by the second waterchannel forming member 491 to flow through the water channel on the sideof the water channel outlet 248. The water flows through the waterchannel on the right side shown in FIG. 12, which is connected to thewater channel outlet 248, in the same manner as through the waterchannel on the above-described left side.

As shown in FIG. 12, three semiconductor modules 500 are arranged on theleft side of the capacitor module 390 and another three semiconductormodules 500 are arranged on the right side of the capacitor module 390.A conventional technology includes a configuration in which waterchannel inlet and outlet are arranged on the same side (for example, thefront surface), six inverted U-shaped water channels are arranged in adirection connecting the inlet with the outlet (for example, right andleft) and are connected in order with return water channels so as todispose six semiconductor modules 500 in each of the inverted U-shapedwater channels. The number of U-shaped return water channels is 11 inthe configuration according to the above-described conventionaltechnology. On the other hand, the number of U-shaped return waterchannels is 3 in the configuration according to the present embodimentshown in FIG. 12: Two return channels 236 (the return channels at theright top and the left top of the channel), and one return channelthrough which the water flow 254 and the water flow 256 pass.

While the configuration according to the above-described conventionaltechnology includes 11 U-shaped water channels, the configurationaccording to the present embodiment shown in FIG. 12 includes 3 U-shapedwater channels. Therefore, pressure drop due to diversion of water flowcan be significantly reduced in the configuration according to thepresent embodiment shown in FIG. 12. The reduction in the pressure dropequalizes the speed of the water flowing through the inlet and the speedof the water flowing through the outlet. As a result, the coolingefficiency by the cooling water will not decrease so much.

As shown in FIGS. 11 and 12, the capacitor module 390 is provided withwater channels on its both right and left sides and on its front (thewater flow 255). Through the thermal conduction material 600, thecapacitor module 390 is also cooled by the cooling water flowing throughthe water channels.

As shown in FIG. 11, also referring to FIG. 5, the upper surface of thecapacitor module 390 occupies a considerably large area of the electricpower conversion apparatus 100. Therefore, an effective use of the uppersurface of the capacitor module 390 is one of the characteristicfeatures of the present embodiment. More specifically, the upper surfaceof the capacitor module 390 is provided with the driver board 386(corresponding to the driver board 74 shown in FIG. 2) thereon. On thedriver board 386, the driver ICs 387 are mounted. The control board 372is provided on the driver board 386 via a connecting member. Both of theboards 386 and 372 are electrically connected with each other via thesignal connector 388 (see FIG. 5). On the control board 372, the controlboard ICs 373 are mounted. In the present embodiment, as describedabove, the upper surface of the capacitor module 390 is thus effectivelyused by providing the driver board and the control board thereon.

More specifically, the left semiconductor modules (for U1-phase,V1-phase, and W1-phase) shown in FIG. 11 correspond to the firstinverter circuit 45 shown in FIG. 3, while the right semiconductormodules (for U2-phase, V2-phase, and W2-phase) shown in FIG. 11correspond to the second inverter circuit 46 shown in FIG. 3. Normally,the driver board 386 is provided for each of the first inverter circuit45 and the second inverter circuit 46. However, in the presentembodiment, the driver board bridges between the first inverter circuit45 including the left three semiconductor modules 500 shown in FIG. 11and the second inverter circuit 46 provided on the right side (see FIG.3). Therefore, the single driver board 386 is only necessary for twoinverter circuits, i.e., the first inverter circuit and the secondinverter circuit.

As shown in FIG. 10, the lower case 142 forms and functions as a channelcase (the water channel 237 in FIG. 10) and as the capacitor moduleinsertion part 147. Therefore, the lower case 142 functions as thechannel case and as positioning of the capacitor module 390, therebyenabling an easy positioning of the capacitor module.

As known from the arrangement of the semiconductor modules 500 and thecapacitor module 390 of the electric power conversion apparatus shown inFIG. 7 and the arrangement of the positive terminal 532 and the negativeterminal 572 of each semiconductor module 500 shown in FIG. 13, thecapacitor module 390 is arranged to face the fins (side B) 562.Therefore, the positive terminal and the negative terminal of thecapacitor module 390 are connected with the positive terminals 532 andthe negative terminals 572 of the semiconductor modules 500 throughdirect current bus bars that are equal to each other in length. Thismakes wiring easy as follows. One of the two direct current bus barsthat are equal to each other in length and in structure bridges betweenthe positive terminal 532 and the positive terminal of the capacitormodule 390. The other of the two bridges between the negative terminal572 and the negative terminal of the capacitor module 390. The directcurrent bus bars that are identical in shape, which is a simplestructure, connect between the positive terminals and between thenegative terminals of the capacitor module and each semiconductormodule, so as to achieve wiring with low inductance.

FIG. 21 is a perspective view showing a structure of a terminalconnection between the semiconductor module and the capacitor moduleaccording to the present embodiment. FIG. 21 shows one side of thestructure in which the semiconductor modules 500 sandwich the capacitormodule 390.

A direct current bus bar 393 protrudes from the capacitor module 390,and is provided with a positive terminal 394 and a negative terminal 395of the capacitor module at the end thereof. The positive terminal 394and the negative terminal 395 are each provided with comb-like terminalsset up vertically at the tip thereof. A thin, plate-shaped capacitormodule terminal insulation part 396 is mounted to the direct current busbar 393 between the positive terminal 394 and the negative terminal 395so as to ensure insulation between these terminals. The thin,plate-shaped terminal insulation part 396 is inserted into the insertionhole 583 provided on the upper side of the semiconductor module 500 soas to determine the position of terminal connection between thesemiconductor module 500 and the capacitor module 390.

This positioning stabilizes the connections between the positiveterminal 532 of the semiconductor module and the positive terminal 394of the capacitor module and between the negative terminal 572 of thesemiconductor module and the negative terminal 395 of the capacitormodule. In other words, the comb-like terminals are tightly attachedwith each other, thereby making a subsequent operation, for example,soldering easy and firm. The connecting terminals of the capacitormodule 390 and the semiconductor module are each made comb-shaped so asto make welding or other fixing method of the connecting terminals easy.As illustrated, since the positive terminal 532 and the negativeterminal 572 of the semiconductor module are arranged in parallel to theside of the capacitor module 390, which faces to the semiconductormodule, the positive terminal 394 and the negative terminal 395 of thecapacitor module can be provided with the same protrusion configuration.Since the plurality of semiconductor modules 500 are arranged next toeach other along the long side of their fins, the configuration of thedirect current bus bars 393 of the capacitor module for each of thesemiconductor modules can be made identical.

The reduction in inductance of the semiconductor module according to thepresent embodiment is described with reference to FIGS. 22 and 23. FIG.22 is a schematic structural layout illustrating reduction of wiringinductance in the semiconductor module and the capacitor moduleaccording to the present embodiment. FIG. 23 is a schematic equivalentcircuit diagram illustrating reduction of wiring inductance in thesemiconductor module and the capacitor module according to the presentembodiment. Because a transient voltage increase and generation of alarge amount of heat in the semiconductor chip occurs at the time ofswitching action of the upper arm and the lower arm that constitute theinverter circuit, it is desirable that the inductance is decreasedparticularly at the time of switching action. Based on a recoverycurrent 600 of a diode, which is generated upon transient time, theeffect of reduction in inductance will be described with an example ofthe recovery current of the diode 543 (corresponding to the diode 66shown in FIG. 2) of the lower arm.

The recovery current of the diode 543 means current that flows throughthe diode 543 in spite of reverse bias. This is generally said to becaused by carriers filled in the diode 543 in a forward state of thediode 543. When conducting action and blocking action of the upper armand the lower arm that constitutes the inverter circuit are performed ina predetermined order, three-phase alternate current is generated in theAC terminal 582 of the inverter circuit. More particularly, when thesemiconductor chip 537 acting as the upper arm is switched from aconducting state to a blocking state, a return current flows through thediode 543 of the lower arm in a direction for maintaining the current ofa stator coil of the motor generator 92 (see FIG. 2). The return currentis a forward current of the diode 543 and the inside of the diode isfilled with carriers. When the semiconductor chip 537 acting as theupper arm is switched from a blocking state to a conducting state, therecovery current due to above-mentioned carriers flows in the diode 543of the lower arm. During steady operations, one of the upper arm and thelower arm of the upper and lower arms series circuit is in a blockingstate, so that no short-circuit current flows through the upper and thelower arms. However, the current in a transient state, for example, therecovery current of a diode, flows through the series circuitconstituted by the upper and the lower arms.

In the configuration shown in FIGS. 22 and 23, when the IGBT 537(switching semiconductor element) acting as the upper arm of the upperand lower arms series circuit is changed from OFF to ON, the recoverycurrent of the diode 543 flows from the positive electrode terminal 532(corresponding to the terminal 57 of FIG. 2) to the negative electrodeterminal 572 (corresponding to the terminal 58 of FIG. 2) via the IGBT537 and the diode 543 (as indicated by arrows in FIG. 22). At thismoment, the IGBT 541 is in a blocking state. The recovery current flowsas follows. As shown in FIG. 22, in the path from the semiconductor chip537 to the positive electrode terminal 532 and the path from thesemiconductor chip 543 to the negative electrode terminal 572, theconductor plates are arranged vertically and in parallel with eachother, and the same current flows but in opposite directions. Then,magnetic fields generated by the respective currents cancel each otherin the space between the conductor plates, resulting in a decrease ininductance of the current path.

The conductor plate 534 and the positive electrode terminal 532 on thepositive electrode side and the conductor plate 574 and the negativeterminal 572 on the negative electrode side are arranged closely againsteach other. This arrangement is referred to as a laminate arrangement.The laminate arrangement causes an effect of reducing inductance. FIG.23 shows an equivalent circuit of the device of FIG. 22. An equivalentcoil 712 of the conductor plate 534 on the positive electrode side andthe positive electrode terminal 532 and an equivalent coil 714 of theconductor plate 574 on the negative electrode side and the terminal 572interact with each other so as to cancel their magnetic fluxes todecrease inductance.

The path of the recovery current shown in FIG. 22 includes the pathsthrough which the current flows in the opposite directions in paralleland an additional path in the form of a loop. When current flows throughthe loop-shaped path, eddy currents 602 and 601 flow in the fin (side A)and the fin (side B). Due to the effect of canceling magnetic fluxes bythe eddy currents, the inductance in the loop-shaped path is decreased.In the equivalent circuit shown in FIG. 23, the phenomenon in which eddycurrent is generated is equivalently expressed by inductances 722, 724,and 726. These inductances are arranged close to the metal plates thatserve as the fins, so that the eddy current generated by induction andthe generated magnetic flux cancel each other. As a result, theinductance of the semiconductor module is decreased by the effect ofeddy current.

As described above, by the arrangement of the circuitry of thesemiconductor module according to the present embodiment, moreparticularly, by the effect of the laminate arrangement and the effectof eddy current, inductances can be decreased. It is important todecrease the inductance at the time of the switching action. In thesemiconductor module of the present embodiment, the upper and lower armsseries circuit is housed in the semiconductor module. This provides asignificant effect of decreasing inductance in a transient state. Forexample, it is possible to decrease inductance for the recovery currentof the diode that flows through the upper and lower arm series circuit.

Decreasing inductance results in lowering an induction voltage generatedin the semiconductor module and in obtaining a circuitry having a lowloss. In addition, lowering induction results in improving the switchingspeed. When attempts are made to increase capacity by arranging aplurality of the semiconductor modules 500 each including theabove-mentioned upper and lower arms series circuit 50 in parallel andconnecting them to the capacitors 90 in the capacitor module 390,respectively, a decrease in inductance of each semiconductor module 500decreases influence of fluctuation of inductance by the semiconductormodules in the electric power conversion apparatus 100, so that theaction of the inverter device becomes more stable.

When a motor generator is required to have a high capacity (for example,400 A or more), a capacitor is also required to have a high capacity.When a multitude of capacitors 90 are connected in parallel and thedirect current bus bars 393 are arranged in parallel, the positiveelectrode terminal 532 and the negative electrode terminal 572 of eachof the semiconductor modules are connected to each capacitor terminal atan equal distance. That is, the positive terminal and the negativeterminal of each semiconductor module 500 and the terminals of eachcapacitor 90 are connected through DC bus bars (connecting members) 393identical to one another in shape and in length. Such connection canalso be achieved by the structure shown in FIG. 21. This makes thecurrent that flows in each of the semiconductor modules uniformlydistributed, enabling the motor generator to operate in good balance ata low loss. By parallelly arranging the positive electrode terminal andthe negative electrode terminal of the semiconductor module, inductanceis decreased due to the effect of laminate arrangement and it ispossible to operate the motor generator at a low loss.

As described above, the electric power conversion apparatus according tothe embodiment of the present invention uses the double side coolingsemiconductor module so as to improve miniaturization, assemblability,and cooling efficiency. The capacitor module insertion part is providedin the center of the substantially rectangular parallelepiped channelcase in which the water channel inlet and the outlet are provided on thesame side thereof. The water channel that extends from the water channelinlet to the water channel outlet is provided on the both sides of thecenter described above. The plurality of semiconductor modules areslotted in to the water channel along the long side of the fins of thesemiconductor modules. The configuration described above is assumed tobe a basic structure. In the basic structure, the first and secondalternate current connectors are provided on a side other than the sideon which the water channel inlet and the outlet are provided. The directcurrent connector is provided on yet another side.

In this basic structure, the driver board of the upper and lower armsseries circuit incorporated in the semiconductor module is provided onthe upper surface of the capacitor module. The control board is providedon the driver board. Thus, an effective use of the upper surface of thecapacitor module is addressed for the overall configuration.

The configuration of the water channel and the plurality ofsemiconductor modules shown in FIG. 12 reduces the number of U-turns inthe water flow. Accordingly, pressure drop due to diversion of waterflow is significantly reduced. The sandwich configuration of thecapacitor module and the water channel shown in FIG. 12 enables thecapacitor to be cooled by the cooling water flowing through the waterchannel. The arrangement of the positive terminal and the negativeterminal of the semiconductor module shown in FIG. 13 allows the directcurrent bus bars with an identical structure to be used to connect theseterminals with the corresponding terminals of the capacitor module,achieving low inductance wiring. The upper surface of the capacitormodule is effectively utilized by providing the driver board and thecontrol board thereon. Even if the electric power conversion apparatusis configured to include two inverter circuits, a single driver boardcan be used as a common driver board. The positioning of the capacitormodule is secured and made easy by providing the capacitor moduleinsertion part in the water channel chassis formed by the lower case.

As shown in FIG. 14, the IGBT of the upper arm and the IGBT of the lowerarm incorporated in the semiconductor module have their length L alongthe vertical direction, and are arranged along the direction of waterflowing through the water channel. Similarly, the diodes of the upperarm and the lower arm with their length M along the vertical directionare disposed below the IGBTs. Therefore, there is no unnecessary lengthin the vertical direction of the semiconductor module, leading tominiaturization. The IGBT, which is to be cooled primarily, occupies anarea of the water channel corresponding to the length L (the verticallength of the fin), which is longer than the length M. This contributesto improvement in the cooling efficiency.

Another example of the arrangement of the positive and the negativeterminals of the semiconductor module according to the presentembodiment will now be described with reference to FIG. 24. Thesemiconductor module shown in FIG. 21 has the structure in which thepositive terminal 532 and the negative terminal 572 are arranged so thatthe comb-like terminals which are set up vertically are arranged alongthe direction of the water flowing through the fin (side A) 522 (seeFIG. 13). As shown in FIG. 24, on the other hand, the comb-liketerminals of the positive terminal 532 and the negative terminal 572 areconfigured to face each other along the short side of the semiconductormodule. That is, the teeth of the comb-shaped positive terminal 532 arearranged along the direction of the water flow on the side of the fin(side A) 522, while the teeth of the comb-shaped negative terminal 572are arranged along the direction of the water flow on the side of thefin (side B) 562. The teeth of the comb-shaped positive terminal and theteeth of the comb-shaped negative terminal face each other along theshort side of the semiconductor module. Only difference between theconfigurations shown in FIGS. 24 and 21 is the arrangement of thepositive terminal 532 and the negative terminal 572. It is to be notedthat the arrangement of other terminals may differ to a certain extent.

The conducting plate 534 (positive electrode side) and the conductingplate 574 (negative electrode side) are each provided with bends so asto form the comb-shaped terminals facing each other as illustrated. Theterminal insulation part insertion hole 583 is provided between theconducting plates 534 and 574 of the terminals 532 and 572 of thesemiconductor module so as to correspond to the terminal insulation part396 of the capacitor module. In accordance with the arrangement of thepositive and negative terminals of the semiconductor module 500described above, the positive terminal 394 and the negative terminal 395of the capacitor module 390 are arranged. More specifically, the anglesbetween the direct current bus bar 393 and the positive and negativeterminals and between the direct current bus bar 393 and the terminalinsulation part are shifted by 90 degrees to the arrangement shown inFIG. 21. That is, the example of another configuration shown in FIG. 24can be achieved only by changing the configuration of the positive andthe negative terminals of the semiconductor module and the capacitormodule.

Configuration examples of a water channel and a plurality ofsemiconductor modules according to the present embodiment will now bedescribed with reference to FIGS. 25A to 26B. FIGS. 25A to 25C showexplanatory diagrams illustrating configuration examples of a waterchannel and a plurality of semiconductor modules according to thepresent embodiment. FIGS. 26A and 26B show explanatory diagramsillustrating other configuration examples of a water channel and aplurality of semiconductor modules according to the present embodiment.

In FIGS. 25A to 26B, reference numeral 142 designates a lower case; 226designates a front inlet water channel; 227 designates a front returnwater channel; 228 designates a front outlet water channel; 236designates a rear return water channel; 237 designates a semiconductormodule insertion channel; 246 designates a water channel inlet; 248designates a water channel outlet; 258 designates a water flow; 390designates a capacitor module; 490 designates a first water channelforming member; 491 designates a second water channel forming member;500 designates a semiconductor module; and 600 designates a thermalconduction material.

FIG. 25A illustrates the configuration of the water channel and thesemiconductor modules shown in FIG. 12 whose structure and function aredescribed with reference to FIG. 12. FIG. 25B illustrates a variation ofthe configuration of the water channel which intends to improve coolingefficiency of the capacitor module and to reduce pressure loss of thecooling water flowing through the water channel. The variation shown inFIG. 25B is explained as follows in contrast to the example in FIG. 25A.In FIG. 25A, three semiconductor modules are inserted into the inletwater channel 226. As shown in FIG. 25A, the cooling water first coolsthe semiconductor modules provided close to the inlet water channel 226,and then cools the semiconductor modules provided close to the outletwater channel 228. Therefore, temperature of the cooling water that isexposed to the semiconductor modules deviates between vicinity of theinlet water channel 226 and vicinity of the outlet water channel 228,resulting in nonuniformity of cooling.

In FIG. 25B, on the other hand, the first water channel forming member490 is provided in the rear so as to form the return water channels 236.Therefore, one side, that is, the fin (side A) 522 or the fin (side B)562 shown in FIG. 13, of the semiconductor modules 500 provided invicinity of the inlet water channel 226 and the outlet water channel 228is cooled first, and the other side is cooled last. This has theadvantage of relative uniformity in the cooling of the semiconductormodules 500.

FIG. 25C illustrates a variation of the water channel in which thereturn water channels 236 are provided in the rear as in FIG. 25B, aswell as the first water channel forming member 490 and the second waterchannel forming member 491 are disposed as illustrated. A plurality ofsemiconductor modules 500 are divided into three units each providednear each side of the rectangular case. For example, the semiconductormodules 500 are divided into the three units so as to include one of thesemiconductor modules of U-phase, V-phase, and W-phase, assuring thermalbalance for each of the phases. This has the advantage of preventing anyone of the phases from being heated to a high temperature.

FIGS. 26A and 26B show other variations of the water channel in whichthe water channel inlet 226 and the water channel outlet 228 are notprovided with water channel forming members thereat, but a water channelis provided in the rear. In the variation shown in FIG. 26A, the waterchannel forming members 490 and 491 are omitted all through the waterchannel from the water channel inlet to the water channel outlet,reducing production cost. In comparison with the water channels shown inFIGS. 25A to 25C, the number of turning points in the water channel canbe reduced, and by branching the water flow, the cooling water flowsslower through each water path, reducing the pressure loss in the waterchannel.

FIG. 26B shows a variation in which the semiconductor modules for eachof the phases are provided along each of the sides of the water channel.In comparison with the variations in FIGS. 25A to 25C, the number ofturning points in the water channel can be reduced, and by branching thewater flow, the cooling water flows slower through each water path,reducing the pressure loss in the water channel.

According to the above explained embodiments of the present invention,the water channel case which also functions as the lower case isprovided with openings in which the semiconductor modules and thecapacitor module are arranged on the substantially same plane, so thatthe semiconductor modules are arranged to sandwich the capacitor module.This arrangement results in improvement in miniaturization, coolingefficiency, assemblability, and product reliability of the electricpower conversion apparatus.

The above-described embodiments are examples, and various modificationscan be made without departing from the scope of the invention.

What is claimed is:
 1. A power semiconductor module, comprising: aplurality of power semiconductor elements that constitute an upper armcircuit and a lower arm circuit; and a conducting plate that iscontinuous with a terminal for supplying direct current power to thepower semiconductor elements, wherein: the terminal includes a first DCterminal and a second DC terminal; the conducting plate includes a firstDC conduction plate and a second DC conduction plate; the first DCconduction plate comprises a protruded portion that has a shapeprotruded to the second DC conducting plate, and in the protrudedportion the first DC terminal is connected with the first DC conductionplate; each of the first DC conduction plate and the second DCconduction plate includes a main surface that is wider than othersurfaces of the conducting plate and a side surface that is narrowerthan the main surface; the side surface of the protruded portion and theside surface of the second DC conduction plate are formed so as not toface to one another, the side surface of the first DC terminal and theside surface of the second DC terminal are formed so as to face to oneanother.
 2. The power semiconductor module according to claim 1, furthercomprising: an AC terminal that transmits alternating current powergenerated through switching operation of the plurality of powersemiconductor elements, wherein: the first DC terminal is disposedbetween the second DC terminal and the AC terminal.
 3. The powersemiconductor module, according to claim 1, wherein: the first DCconduction plate has a bending portion that is formed between theprotruded portion and the first DC terminal.
 4. The power semiconductormodule, according to claim 1, further comprising: a mold resin thatseals part of the conduction plate, wherein the protruded portion isdisposed inside the mold resin, and the first DC terminal and the secondDC terminal are disposed outside the mold resin.
 5. An electric powerconversion apparatus, comprising: a power semiconductor module accordingto claim 1; a capacitor that smoothes direct current power; and a DC busbar that connects the power semiconductor module with the capacitor,wherein: the DC bus bar comprises a first bus bar terminal that isconnected with a main surface of the first DC terminal and a second busbar terminal that is connected with a main surface of the second DCterminal.